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5.0 from 6 votes

Small-batch Monster Cookie Bars

These small-batch monster cookie bars are a super simple one-bowl dessert that require zero flour. They’re big on peanut butter flavor and packed full of M&Ms and melty chocolate chips.

Prep Time
10 mins
Cook Time
10 mins
Additional Time
45 mins
Total Time
1 hr 11 mins
Servings: 6 to 8 bars
Calories: 381 kcal
Course: Dessert
Cuisine: American

Ingredients

  • 3 tablespoons (42g) salted butter softened*
  • 1/2 cup (132g) peanut butter creamy or chunky*
  • 1/3 cup (67g) granulated sugar
  • 1/3 cup (67g) brown sugar
  • 1 large egg
  • 1/2 teaspoon vanilla extract
  • 1 1/2 cups (130g) quick/instant oats *
  • 1/2 teaspoon baking soda
  • 1/2 cup (85g) M&M’s plus more for topping
  • 1/3 cup (56g) chocolate chips

Instructions

    Cup of Yum
  1. Preheat your oven to 350°F. Lightly grease and line a loaf pan with parchment paper.
  2. In a medium bowl, combine softened butter, peanut butter, and granulated and brown sugars. Beat until well-combined and slightly lightened in color, about 1 minute.
  3. Add egg and vanilla and mix until well-combined.
  4. Add oats and sprinkle baking soda over the top. Mix until well combined.
  5. Add M&M’s and chocolate chips and use a wooden spoon or spatula to mix.
  6. Transfer mixture to prepared baking pan and press dough out into an even layer. Sprinkle a few extra M&M’s over the top if desired, and bake for 15 to 18 minutes, until the edges are lightly browned (the center will still look pale and slightly underdone). Do not overbake!
  7. Allow bars to cool in the pan for about 45 minutes so they can firm up before transferring to a cutting board and slicing.
  8. Serve and enjoy!

Notes

  • Store bars at room temperature in an airtight container for 3 to 4 days or freeze in a freezer bag for up to 2 months.
  • *If using unsalted butter, add 1/8 teaspoon of salt along with the oats and baking soda.
  • *These bars have not been tested with natural peanut butter. 
  • *Old-fashioned/rolled oats may also be used.
  • Nutritional information is for 8 servings.

Nutrition Information

Serving 1bar Calories 381kcal (19%)

Nutrition Facts

Serving: 6to 8 bars

Amount Per Serving

Calories 381

% Daily Value*

Serving 1bar
Calories 381kcal 19%

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