Monster Cookie Bars Recipe

A close-up of a monster cookie bar topped with chocolate chips and colorful M&Ms on a white plate.

5 from 1 vote

With their thick layers of peanut butter dough, scattered chocolate, and colorful candies, Monster Cookie Bars bake into chewy, golden bars with crispy edges and soft, tender centers.

Prep Time10

Cook Time15

Cool Time30

Total Time55

Course: Brownies & Bars, Dessert

Cuisine: American

Diet: Vegetarian

Servings: bars

Calories: 251kcal

Author: Andrea

Ingredients

2 cups all-purpose flour
1 1/2 cups quick rolled oats
1 cup sugar
1 cup brown sugar
2/3 cup peanut butter creamy or chunky
1 cup (2 sticks) butter room temperature
2 eggs
1 tsp baking soda
1/2 tsp salt
1 teaspoon vanilla extract
1/4 cup peanuts chopped
1/4 cup chocolate chips a mix of regular and mini
1/4 cup M&Ms a mix of regular and mini

Peanut Butter Topping

2/3 cup Reese's peanut butter
1 1/2 cups confectioner's sugar
1/3 cup milk more if needed
1/4 tsp salt
1/4 tsp vanilla
1/2 cup chocolate chips a mix of regular and mini
1/2 cup M&M candies a mix of regular and mini

Instructions

Preheat the oven to 350 degrees Fahrenheit (177 degrees Celsius). Lightly grease (or cover with parchment paper) a full-size cookie sheet with sides.
In a medium-sized mixing bowl, whisk together the oats, flour, baking soda, and salt. Set aside.
In the bowl of a stand mixer, beat together the peanut butter, butter, and sugars for 1 minute. Turn the speed to low and add one egg at a time. Add the vanilla and mix until combined.
Remove the bowl from the stand mixer. Fold in the dry ingredients, then the chopped peanuts, chocolate chips, and M&Ms. Pour onto the prepared pan and pat down until even. Use your hands to gently press the mixture into the pan, then smooth it out with a spatula for an even surface. Place in the oven and bake for 15–18 minutes, or until the top begins to brown.
While the bars are baking, in a medium-sized mixing bowl, combine all of the topping ingredients. Using a hand mixer, beat until smooth (it should be a spreadable consistency, but it will also melt and get shiny on contact). Set aside until needed.
Remove the bars from the oven and place the pan on a wire rack. Allow to cool for 8 minutes before spreading the peanut butter topping over the entire sheet. It should become smooth and melty. Spread until even. Sprinkle the remaining chocolate chips and M&Ms over the top. Allow to cool for 30–40 more minutes before cutting into bars.

Notes

STORE the bars in an airtight container at room temperature for up to 4–5 days after they’ve cooled completely. For longer storage, place them in a sealed container or zip-top bag and FREEZE for up to 2 months.

To thaw, leave at room temperature for 1–2 hours or microwave individual squares for 10–15 seconds. To REHEAT a larger batch, warm them in a 300 degrees Fahrenheit (149 degrees Celsius) oven for 8–10 minutes.

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