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Monster Cookie Bars
4.6 from 21 votes

Monster Cookie Bars

Loaded with chocolate chips and M&Ms, Monster Cookie Bars are thick & chewy, and oh-so-good! These peanut butter oatmeal cookie bars can easily be adapted into a festive treat for any holiday, from the 4th of July to Christmas - and did I mention you only need one bowl?!

Prep Time
15 mins
Cook Time
15 mins
Total Time
30 mins
Servings: 48 bars
Calories: 155 kcal
Course: Baked Goods
Cuisine: American

Ingredients

  • ½ cup unsalted butter at room temperature, divided, 1 tablespoon
  • 1½ cups peanut butter creamy
  • 1 cup brown sugar packed
  • 1 cup granulated sugar
  • 3 egg large
  • 1 teaspoon vanilla extract pure
  • 1 cup all-purpose flour
  • 3½ cups old fashioned oats
  • 2 teaspoons baking soda
  • ½ teaspoon kosher salt
  • 12 ounces semi-sweet chocolate chips use Guittard brand
  • 1 M&M's 12.6-ounce bag; customize colors for occasions
  • chocolate frosting optional - see note below
  • Sprinkles optional - see note below

Instructions

    Cup of Yum
  1. Preheat oven to 350° F. Lightly butter a 12'' x 17'' jelly roll pan with 1 tablespoon of the butter. Set aside.
  2. In the bowl of a stand mixer, cream together remaining 1/2 cup butter, peanut butter, brown sugar, and sugar. Add eggs and vanilla, and mix until incorporated. Add flour, oats, baking soda, and salt, and mix again until incorporated.
  3. Reserve about 1/2 cup each of the chocolate chips and M&M's, and then fold the remaining into the batter with a spatula. Press the batter evenly into prepared pan. Sprinkle the reserved chocolate chips and M&M's over the top, pressing them in slightly. Bake for 14 to 15 minutes. These bars are meant to be chewy; do not over bake! Remove from oven and let pan cool completely on wire rack. Then cut into individual bars.

Notes

  • These bars are fabulous just the way they are, but if you want to add a little more festivity for the 4th of July, add some chocolate (or white) frosting and sprinkles! My favorite chocolate buttercream would be great, or simply use a can of fudge frosting from the baking aisle at the grocery store. Place frosting in a pastry bag fitted with a medium star tip and swirl the frosting onto the top of each bar. Add some red, white, and blue sprinkles, and you're set for a celebration!
  • Adapted from the recipe box of Blake’s cousin, Melanie Sorenson.

Nutrition Information

Serving 1 Calories 155kcal (8%) Carbohydrates 21g (7%) Protein 4g (8%) Fat 7g (11%) Saturated Fat 2g (10%) Polyunsaturated Fat 4g (24%) Cholesterol 12mg (4%) Sodium 112mg (5%) Fiber 2g (8%) Sugar 13g (26%)

Nutrition Facts

Serving: 48 bars

Amount Per Serving

Calories 155

% Daily Value*

Serving 1
Calories 155kcal 8%
Carbohydrates 21g 7%
Protein 4g 8%
Fat 7g 11%
Saturated Fat 2g 10%
Polyunsaturated Fat 4g 24%
Cholesterol 12mg 4%
Sodium 112mg 5%
Fiber 2g 8%
Sugar 13g 26%

* Percent Daily Values are based on a 2,000 calorie diet.