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Homemade Protein Cereal Bars

Protein cereal bars, the way they SHOULD be.

I recently got my hands on Cinnamon Toast Crunch Protein Bars, as well as Golden Grahams Protein Bars. When I say I’ve never been more excited to try a snack in my life, I mean it.

If you want to see me try them in real-time, you can see my review here: 

But allow me to summarize these protein bars for you: they were awful.

I LOVE cereal. So much. But these high-protein versions tasted absolutely nothing like the cereal I know and love.

After trying these protein bars, I vowed to create my own versions of cereal protein bars the way they SHOULD taste, and my friends, I’m so excited to bring these to you.

We’re going to make two different types of protein cereal bars: classic milk n’ cereal using Cinnamon Toast Crunch, and s’mores using Golden Grahams:

These bars are SO good.

Now, I’ll be honest and say that the nutrition is not as impressive as a typical protein bar. The protein is a little bit lower and the sugar is higher than most bars, but that’s because I wanted these to be authentic cereal bars.

These shouldn’t taste like protein; they should just be delicious! I want these to transport you right back into childhood.

Each bar is 185 Calories, 2.5g Fat, 31g Carbs (17g Sugar), and 11g Protein.

As a treat, that’s really not bad at all! While I’d love to be able to bring the sugar down a bit for ya, we’re using authentic cereal and marshmallows as the base, so there’s really not much we can do there.

But don’t worry- it is totally worth it.


How to make protein cereal bars

Let’s walk through the process of making these bars step-by-step to make things easy for you.

While we’re making 2 different flavors, the process of making the bars exactly the same no matter which route you go.

Step 1: Melt marshmallows and butter

Add marshmallows and butter to a large pot and let them melt over low heat.

Continuously stir to prevent burning until it is completely melted down without any lumps…

Step 2: Fold in a scoop of vanilla protein powder

We’re going to add a scoop of protein powder into the melted marshmallow mixture and fold it in. This is going to create a very thick sauce.

Step 3: Fold the cereal in

It’s going to be very thick, but keep folding the cereal with your spatula until it is all completely covered by the marshmallow mixture.

Step 4: Add your cereal to a baking dish

Lightly spray a baking dish and dump the cereal right into it. To make these bars, we are using a 9x13in baking dish, but there’s notes in the next section about using an 8x8in pan instead.

Spread the cereal to the edges as much as possible using your spatula (you can lightly wet the spatula with cold water if it is too sticky). As you can see, there are going to be some gaps, and it’s going to look like there isn’t enough cereal…

At this stage, I simply used my hands to take some cereal off of thicker areas and added them to fill in the gaps.

It doesn’t need to look totally perfect: we’re making a filling and layering 2 pieces of the bars, so any gaps won’t even be noticable.

When you’re done, it should cover the majority of the dish:

Let this sit out at room temperature for 30-60 minutes to allow it to harden.

Step 5: Make the protein filling

Whether you’re going with the chocolate or milk filling, the process is the same. Mix all the dry ingredients together, then add milk one tablespoon at a time until you have a thick but spreadable frosting.

Use your silicone spatula to spread it over the top of the entire batch:

Let this sit for another 30 minutes to allow the frosting to solidify.

Step 6: Slice and assemble

At this stage, the bars will be completely solidified and ready to cut. You can use a butter knife to cut the bars into as many as you’d like to make!

If you plan to make 8 protein cereal bars, cut the batch into 16 total (this batch pictured was only 14 total).

Once cut, sandwich them together so the frosting sits in the middle.

Now they’re ready to eat!

The frosting shouldn’t be too soft, but if it is, you can throw these into the fridge for a little bit to help them solidify.

I don’t mind the small gap in the center, but if you’re a perfectionist, you can squeeze ’em down to make them a bit more uniform.

Step 7 (Optional): Top with chocolate drizzle

To help make these look even prettier, I lined the bars up on parchment paper, melted down some chocolate, and drizzled it over the top.

I didn’t measure the exact amount I used, and this is certainly not necessary, but it helps them look even prettier!

Just melt down chocolate in the microwave and use a spoon to drizzle right over the top of the protein cereal bars.


Making these protein cereal bars without the frosting

When I made a second batch of these bars, I made them in an 8x8in pan instead (like I use for my famous Protein Brownies) to make thicker bars.

Using a small pan makes it much easier to add the cereal because you don’t need to spread it nearly as much, but you lose the ability to create the sandwich frosting layer in the center.

If you follow the recipe exactly as is, you can then cut these into 8 thicker bars:

These taste just like Rice Krispies Treats!

Without the frosting, each bar drops down to 150 Calories, but only 5g of Protein.

If you’re looking for a simple treat and don’t need a ton of protein, this is the way to go!

If you make these smaller bars and still want to add the frosting, you can still spread it right on the top. These protein cereal bars aren’t as neat and tidy with the frosting right on the top, but it’s certainly easier.


Making substitutions for these protein cereal bars

There are not a lot of ingredients to this recipe, so let me break down possible substitutions for reach.

I always recommend following the recipe as closely as possible, if you can help it.

The Protein Powder

I used PEScience vanilla protein powder in this recipe, which has been my go-to protein for a long time now. It’s a blend of whey & casein protein, and the addition of casein makes for a very smooth, frosting-like consistency. Quest is another brand I can highly recommend as it is also a blend!

Here are some common substitutions:

  • Whey Protein: Whey is very sticky on its own, so the final product may not be as ideal. It will definitely work in the bars, since those are sticky anyway. For the frosting, it may not be as smooth of a frosting, unfortunately. Worth a try if it’s all you have, though!
  • Casein Protein: A casein protein powder should work very well in this recipe, especially for the frosting.
  • Vegan Protein: I don’t know if a vegan protein powder will work as well, because they tend to be extremely absorbent- that will change the ratios needed for this recipe. If you need a vegan version of protein cereal bars, I recommend checking out these bars from Armon at The Big Man’s World.

The Cereal

You can use ANY cereal you’d like in this recipe! The amount should generally stay the same, but you may find wanting to use slightly more or slightly less depending on the cereal. Rice Krispies, for example, are much smaller and you may find needing a bit more.

Protein hack: Use a high-protein cereal like Magic Spoon to up the protein in these cereal bars even more! Fun fact: you can use the code “cheatday” to get free shipping on any Magic Spoon order ?

Marshmallows & Butter

I use mini marshmallows in this recipe, but you can use any marshmallows you have- mini marshmallows are just the easiest to melt down! If you have fluff, you can definitely use that as well.

For the butter, I use a “butter spread” made by Country Crock, because it is only 50 calories per tablespoon (vs butter that has 100 calories per tablespoon). You can use any butter or butter substitute you want here- it’s just to help melt down those marshmallows. Regular butter, coconut oil, margarine, etc, should all work fine, especially because it’s a pretty small amount.


How to store protein cereal bars

If you’re making a batch of these protein cereal bars, odds are that you aren’t going to eat them all in one day.

These are best eaten the same day, but they will keep fresh for a few days.

The first time I made these bars, I sealed them in an airtight container and left them on the counter, and they got way too soft. The cereal lost its crunch and turned pretty stale!

For best results, store these in the fridge. I actually just stored them uncovered on a plate, and they were great for 2 days (I ate them all after 2 days, so I can’t speak to any time beyond that). The frosting will dry out a tad, but not to the point where it’s hard. If you find it hardening too much, you can cover the bars. I just didn’t want to risk it due to my first run getting too soft when covered.

These bars don’t need refrigeration and can sit out at room temperature for a day or two with no problem. Just don’t completely cover them, because the added moisture from the frosting gets locked there and leads to soggy cereal. Bleh.

Storage tip: You can mix your frosting and store it in a separate container, then spread it over the leftover bars before eating! If you go the route of making these bars in an 8x8in pan to make thicker bars, that strategy works out great.


Okay, let’s make some protein cereal bars! If you make these bars, I’d love to see those creations! Tag me on Instagram so I can see ’em.

Homemade protein cereal bars

Protein Cereal Bars (Milk N' Cereal & S'mores)

Prep Time: 10 minutes
Additional Time: 1 hour
Total Time: 1 hour 10 minutes

Cinnamon Toast Crunch & Golden Grahams protein bars have recently hit the market, but they seriously missed the mark- so we're going to make our own! We'll make the classic "Milk N' Cereal Bars" with Cinnamon Toast Crunch, and a S'mores version with Golden Grahams!


Cereal Bar Base

Milk Frosting (if making milk n' cereal bars)

Chocolate Frosting (if making s'mores bars)

Optional Topping

  • Milk Chocolate or White Chocolate for drizzle on top


  1. In a large bowl, weigh out the 3.5 cups of cereal and set aside. Take a 9x13 dish (or 8x8 if you're going that route- see the breakdown above) and lightly spray with nonstick spray. The process goes quickly, so we want to have the dish ready to go.
  2. Take a large pot and put it on the stove over low heat (we're going to be adding all the cereal to the pot, so make sure it is large enough). Add the butter and let that melt, which should only take one minute.
  3. Add the marshmallows to the pot, stirring consistently to prevent burning. Continue until there are no lumps left and the marshmallows are completely melted.
  4. Add one scoop of protein to the pot and stir it in to fully mix it. This is going to leave us with a thick sauce that looks almost like melted white chocolate.
  5. Pour your cereal into the pot and use a silicone spatula to fold the marshmallow mixture until the cereal is fully coated. It'll be very thick, but enough to coat all of the cereal we're adding.
  6. Remove from the heat and add all of the cereal mixture into your sprayed baking dish. It's not going to seem like enough, but trust me here. Use a spatula to press down the cereal mixture until it extends to all the corners (you can wet the spatula with cold water if it's too sticky). If you're using a 9x13 dish as I did, it's going to leave you with some gaps. I simply used my hands to take some pieces of cereal off of certain areas to fill in the gaps (see all the photos above).
  7. Let sit for 30 minutes to solidify.
  8. After 30 minutes, we'll make the frosting layer. Whether you're making the classic milk frosting or the chocolate frosting, the process is the same- add all the dry ingredients to a large bowl and mix them together. Then add the milk one tablespoon at a time until you have a thick & spreadable frosting. Depending on the type of protein powder you have, you'll need more or less milk, so I like to add one tablespoon at a time to be able to judge as I go. The amounts listed are exactly what I used!
  9. Spread the frosting over the entire pan to completely cover the cereal. Don't worry about it looking pretty at this stage. Let everything sit for another 30 minutes to allow the frosting to set (you can add to the fridge to speed this process if needed).
  10. Now, we're ready to slice. Using a butter knife, cut through the bars. You can make them as large or small as you'd like, but I recommend cutting them into 16 smaller bars. Then, take 2 pieces and sandwich them together so the frosting is in the center, and you have your cereal bar!
  11. Optional: melt chocolate or white chocolate in the microwave and drizzle on top before serving.


  • Storing these bars: If you have leftovers, I recommend simply storing them on a plate in the fridge. These will keep just fine at room temperature as well, but the fridge will keep them fresher. DO NOT store them on the counter in a sealed container. I thought this would be the way to go, but it locks in moisture and actually leads to stale cereal- keeping these bars uncovered will keep them nice and crunchy.
  • I made a second batch in an 8x8 pan to make things easier without having to do any sandwiching. You can then spread the frosting right on top, or save the frosting in a separate container and top the protein cereal bars as you eat them.
  • Like most recipes, things may be a little bit different depending on the type of protein you use. The one I use and recommend is a blend of whey & casein protein, which stays nice and thick. It works VERY well for frosting and I recommend it over just a regular whey protein powder.
  • You can use any cereal you'd like in these, or toss mix-ins (like chocolate chips) right into the bars. Feel free to get creative.
  • The nutrition info below is for the Golden Grahams bars. The Cinnamon Toast Crunch Protein Bars are very similar, but have one less gram of protein and 5 extra calories per bar.

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Nutrition Information
Yield 8 Protein Cereal Bars Serving Size 1 Bar
Amount Per Serving Calories 185Total Fat 2.5gCarbohydrates 31gProtein 11g

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Protein Cereal Bars Recipe

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Thursday 29th of September 2022

Do you think these would last in the freezer? If so, any advice on how to store? I'd rather make a big batch and eat them throughout a few weeks or a month.


Monday 3rd of October 2022

Hmmm, that's a great question. I do think it will work just fine if you freeze them, but I'm worried about how the texture would be once thawed. I've never frozen cereal before so I can't say for sure how it'll turn out, but they'll absolutely last in the freezer if you wrap them in foil and seal them in a ziploc.


Friday 5th of November 2021

Just wanted to let you know that I tried making these cereal bars with 100% whey protein and it turned out very well! I was still able to achieve a nice and smooth frosting consistency, and it worked great with the marshmallow and cereal portion too!


Monday 8th of November 2021

Great to know, thank you so much!

About Matt Rosenman

With over 15 years of experience in health and fitness, Matt Rosenman is the expert voice behind Matt’s philosophy is simple: no foods are off-limits, and a healthy lifestyle shouldn't be complicated or restrictive. As a former certified personal trainer with a bachelor’s degree in Health Behavioral Sciences, Matt brings well-rounded expertise to his blog. From revamping classic recipes with a nutritious twist to breaking down fast food menus, his goal is make healthy living less confusing for everyone. Featured in major publications and with a strong following on social media, Matt is committed to making “healthy” uncomplicated—no matter where you are in your health journey. Join Matt on his mission to simplify health without sacrificing flavor. Learn More

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