These super simple Monster Cookie Bars are ready to bake in just 10 minutes! The chewy oatmeal peanut butter cookie base is full of chocolate chips and M&M’s making them an irresistible treat. This cookie bar recipe is also easy to make gluten-free or double for a crowd. With this recipe, you’ll get perfectly chewy, melt-in-your-mouth Monster Cookie Bars every single time!
Table of Contents
What are Monster Cookies?
Monster Cookies are a peanut butter oatmeal cookie base with chocolate chips and M&M’s. There are quite a few variations out there and I’ve given you some fun ideas below, but in general, this is the starting point for a traditional monster cookie recipe.
What You’ll Love About This Monster Cookie Bar Recipe
- Perfect Texture – The thick, chewy texture is created with rolled oats, flour, and creamy peanut butter. The chocolate chips and M&M’s add delightful crunchy bites throughout each bar. The combo is just SO GOOD!
- Flavor – Oats, peanut butter, semi-sweet chocolate chips, and milk chocolate M&M’s – it’s like a flavor party!
- Playful and Fun Vibe – Cookies with colorful M&M candy in them? So fun. Add in some chocolate chips, too and these treats are basically irresistible.
- Easier than Cookies – No scooping, shaping, or batches. All of the cookie dough goes in one pan and all cooks at the same time. Save time and hassle!
RELATED: Nutter Butter Cookies
Ingredients in Monster Cookie Bars
These cookies are made from ingredients that are likely in your pantry right now. Here’s what you’ll need to make them:
- Butter – Use unsalted butter for best results. You can substitute with plant-based butter, but your cookie bars may be a bit more crumbly in texture.
- Sugar and Dark Brown Sugar – The combination of white and dark brown sugar gives the cookies the caramely richness and perfect amount of sweetness.
- Creamy Peanut Butter – Feel free to use your favorite peanut butter. Any of them will work.
- Egg – The egg is the binder in this recipe. If you need to avoid eggs, try making a flax egg instead.
- Vanilla – The little bit of vanilla extract in the monster cookie dough brings all of the flavors together.
- Flour – All-purpose flour works great in this recipe.
- Old-Fashioned Oats – Also known as rolled oats, they’re thick and chewy and make every bite full of texture.
- Salt, Baking Soda, and Baking Powder
- Semi-Sweet Chocolate Chips
- M&M’s – Use regular M&M’s or Unreal Milk Chocolate Gems that are made with natural dye!
How to Make Monster Cookie Bars
This recipe is a fail-proof guide to making deliciously chewy Monster Cookie Bars that are perfect every single time. Here’s how to do it:
- Preheat the oven to 350 degrees F.
- Cream the butter and sugars together in a bowl with a stand or electric hand mixer until smooth and fluffy.
- Add the peanut butter, egg, and vanilla, and mix on low speed.
- Add the dry ingredients and mix well with the mixer.
- Stir in the chocolate chips and M&M’s, then scoop the cookie dough into a 9×9″ baking pan and smooth the top.
- Bake, cool, cut, and serve!
Recipe Variations
- Make them gluten-free by swapping equal amounts of gluten-free flour with the all-purpose flour in the recipe.
- Substitute the peanut butter with almond butter, sun butter, or cashew butter for a different flavor or to make them peanut-free.
- Use white chocolate chips instead of semi-sweet chocolate chips to add a sweeter vanilla flavor to the cookie bars.
- Add nuts to the cookie dough. Walnuts, pecans, and chopped peanuts would all be fun and tasty additions to the cookie bars.
- Drizzle the top with melted chocolate or caramel before serving.
- Double the recipe. Serving more people? Simply double the recipe and bake them in a 9×13 pan instead of a 9×9 pan.
Storing Cookie Bars
It’s so easy to keep these cookie bars in an airtight container or bag for later! Here’s how to store them:
- Room-Temperature – up to 5 days
- Refrigerate – up to 7 days
- Freeze – up to 3 months
More Dessert Bar Recipes You’ll Love
- Churro Cheesecake Bars
- Pumpkin Swirl Cheesecake Bars
- Mulberry Pie Bars
- Banana Pudding Brownies
- Matcha Brownies Recipe
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Monster Cookie Bars
These super simple Monster Cookie Bars are ready to bake in just 10 minutes! The chewy oatmeal peanut butter cookie base is full of chocolate chips and M&M's making them an irresistible treat. This cookie bar recipe is also easy to make gluten-free or double for a crowd. With this recipe, you'll get perfectly chewy, melt-in-your-mouth Monster Cookie Bars every single time!
Equipment
Ingredients
- 1/4 cup butter
- 1/4 cup sugar
- 1/4 cup dark brown sugar
- 1/3 cup creamy peanut butter
- 1 large egg
- 1 teaspoon vanilla extract
- 3/4 cup flour
- 3/4 cup old fashioned oats
- 1/2 teaspoon salt
- 1/2 teaspoon baking soda
- 1/4 teaspoon baking powder
- 1/4 cup semi-sweet chocolate chips
- 1/4-1/3 cup M&Ms
Instructions
- Preheat the oven to 350 degrees F.
- Cream the butter and sugars together with a stand or electric hand mixer until smooth and fluffy.
- Add the peanut butter, egg, and vanilla, and mix on low speed until completely combined.
- Add the flour, oats, salt, baking soda, and baking powder, and mix well with the mixer.
- Stir in the chocolate chips and M&M’s with a spoon or spatula.
- Scoop the batter into an 8×8 or 9×9 square baking dish and smooth the top.
- Bake for 20-25 minutes until golden brown.
- Allow the bars to cool for at least 30 minutes before cutting and serving.
Notes
Store in an airtight container or bag. Room-temp for up to 5 days, in the refrigerator for up to 1 week, or freeze for up to 3 months.
Double the recipe and make them in a 9×13 pan for a larger batch.
Nutrition
Serving: 1BarCalories: 265kcal
Tried this recipe?Let us know how it was!
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