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Monster Cookie Bars

These Monster Cookie Bars are a chewy, chocolatey delight! Packed with oats, peanut butter, and M&Ms, they’re sure to impress!
Prep Time15 minutes
Cook Time30 minutes
Total Time45 minutes
Course: Dessert
Cuisine: American
Keyword: Chewy, Chocolate, Easy, Peanut Butter
Servings: 16 servings

Ingredients

  • 2 cups all-purpose flour spooned and leveled
  • 2 cups old-fashioned oats
  • 1 teaspoon baking soda
  • 1 teaspoon sea salt
  • 1 cup unsalted butter at room temperature
  • 1 cup creamy peanut butter
  • 1.5 cups packed light brown sugar
  • 0.5 cup granulated sugar
  • 2 large eggs
  • 1 tablespoon vanilla extract
  • 1.25 cups semi-sweet chocolate chips
  • 1.5 cups M&Ms divided
  • Flaky sea salt for sprinkling on bars

Instructions

  • Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving some overhang to make it easier to lift the bars out later.
  • In a large mixing bowl, whisk together the all-purpose flour, old-fashioned oats, baking soda, and sea salt. Set this mixture aside.
  • In another large bowl, beat the unsalted butter, creamy peanut butter, light brown sugar, and granulated sugar together using an electric mixer until the mixture is light and fluffy—about 2-3 minutes.
  • Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract until everything is well combined.
  • Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
  • Using a rubber spatula, gently fold in the semi-sweet chocolate chips and 1 cup of the M&Ms. Reserve the remaining 1/2 cup of M&Ms for topping.
  • Spread the cookie dough evenly into the prepared baking pan. Use the spatula to smooth the top.
  • Sprinkle the reserved M&Ms over the top of the dough, pressing them down slightly. Finish with a light sprinkle of flaky sea salt.
  • Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and a toothpick inserted in the center comes out with a few moist crumbs.
  • Allow the bars to cool in the pan for about 15 minutes. Then, use the parchment paper to lift the bars out of the pan and onto a wire rack to cool completely before cutting into squares.

Equipment

  • Mixing Bowls
  • Whisk
  • Rubber spatula
  • Baking pan
  • Parchment Paper
  • Measuring cups and spoons

Notes

  • For a nut-free version, replace peanut butter with sunflower seed butter.
  • Swap semi-sweet chocolate chips for milk or dark chocolate chips based on preference.
  • Store bars in an airtight container for up to 5 days or freeze for up to 3 months.