These super fun and gooey marshmallow cereal treats are filled with peanut butter, oats, chocolate chips, and M&Ms!

Monster Marshmallow Cereal Treats from

This was one of those recipe ideas that just came to me all of the sudden and then— bam!— I had to have these bars immediately.

Rice crispy treats have always been a weakness of mine, but this trashed up, everything-but-the-kitchen sink version sounded too fun to not make right away. As a recipe blogger focusing mostly on sweet treats, I get a lot of sugar cravings. It just comes with the territory. I shrug most of my cravings aside or save them for a special occasion, but everyone once in a while one gets the better of me and I just can’t resist.

Like these rice crispy treats!

Monster Marshmallow Cereal Treats from

The premise for these cereal bars is that they’ve got all the mix-ins of the classic monster cookie— peanut butter, oats, chocolate chips, and m&ms. But instead of being mixed into cookie batter, I dumped them into a pot filled with gooey marshmallows, crispy rice cereal, and cheerios.

Monster Marshmallow Cereal Treats from

It was a good decision, if I do say so myself.

Monster Marshmallow Cereal Treats from

And the combo is one wonderful gooey mess. These bars have it all!

Feel free to play around with your mix-ins and customize these cereal bars to whatever you’re craving. You can use everything from shaved coconut to chopped up candy bars to even your favorite cereal, you really can’t go wrong.

Monster Marshmallow Cereal Treats from

I think the only wrong move would be to ignore that sugar craving. (Because surely right now you’re jonesing pretty bad. If not, then I’m really bad at my job.)

So go ahead. Give in. These ooey gooey monster marshmallow cereal treats are waiting for you!

Monster Marshmallow Cereal Treats from

Monster Marshmallow Cereal Treats from

Monster Marshmallow Cereal Treats

Servings: 16 bars
Cook Time: 10 minutes
Rest Time: 30 minutes
Total Time: 40 minutes
Gooey marshmallow cereal treats filled with peanut butter, oats, chocolate chips, and M&Ms!


  • 5 tablespoons butter (70 grams)
  • 1/3 cup creamy peanut butter (90 grams)
  • 10 cups mini marshmallows , divided (430 grams)
  • 3 cups crispy rice cereal (80 grams)
  • 3 cups toasted whole grain oats cereal (84 grams)
  • 1/2 cup old fashioned oats (50 grams)
  • 1/4 cup mini chocolate chips (60 grams)
  • 1/4 cup mini M&Ms (42 grams)
  • 1/3 cup chopped peanuts (47 grams)
  • Additional mini chocolate chips, M&Ms, peanuts, etc. for sprinkling on top (optional)


  • Line a 9-inch square pan with greased foil or parchment paper.
  • In a large pot set over medium low heat, melt butter, peanut butter, and 8 cups of the mini marshmallows, stirring frequently.
  • Once completely melted, add crispy rice cereal, whole grain oats cereal, and oats and stir until combined.
  • Add the remaining 2 cups mini marshmallows, mini chocolate chips, mini M&Ms, and chopped peanuts and gently stir until incorporated.
  • Immediately dump into the prepared pan. Use a greased spatula or fingers to gently press mixture evenly into the pan, careful to too compact it too tightly. Sprinkle with additional mini chocolate chips, M&Ms, peanuts, etc. if desired.
  • Let sit for 30 minutes (or in the fridge for 10 minutes), then slice and serve. Store in an airtight container.
Calories: 248kcal, Carbohydrates: 39g, Protein: 4g, Fat: 10g, Saturated Fat: 4g, Cholesterol: 10mg, Sodium: 109mg, Potassium: 96mg, Fiber: 1g, Sugar: 22g, Vitamin A: 253IU, Vitamin C: 1mg, Calcium: 32mg, Iron: 2mg
Cuisine: American
Course: Dessert
Author: Annalise Sandberg
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