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Soft Baked Monster Cookie Bars with M&Ms: Easy 30-Min Recipe

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These soft baked monster cookie bars are packed with peanut butter, oats, M&Ms, and chocolate chips. Ready in 30 minutes with no chilling required, they have chewy edges and fudgy centers—perfect for parties, lunchboxes, or a quick sweet treat.

Ingredients

Scale
  • 1 cup (2 sticks / 226g) unsalted butter, melted
  • 1 cup (200g) light brown sugar, packed
  • ½ cup (100g) granulated sugar
  • 1 cup (250g) creamy peanut butter (processed, not natural)
  • 2 large eggs, room temperature
  • 2 teaspoons vanilla extract
  • 1½ cups (190g) all-purpose flour
  • 1 cup (90g) old-fashioned rolled oats
  • ½ cup (45g) quick oats
  • 1 teaspoon baking soda
  • ½ teaspoon salt
  • 1½ cups (270g) M&Ms (plus ¼ cup reserved for topping)
  • ½ cup (85g) semi-sweet chocolate chips

Instructions

  1. Preheat oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving 2 inches overhang on the long sides. Lightly spray with non-stick cooking spray.
  2. In a large bowl, whisk together melted butter, brown sugar, and granulated sugar until smooth (about 30 seconds).
  3. Add peanut butter and whisk until fully incorporated. Add eggs and vanilla extract, whisk until smooth and glossy.
  4. In a separate bowl, whisk together flour, old-fashioned oats, quick oats, baking soda, and salt.
  5. Add dry ingredients to wet mixture in two additions, folding gently with a rubber spatula until just combined. Do not overmix.
  6. Fold in 1½ cups M&Ms and semi-sweet chocolate chips. Reserve ¼ cup M&Ms for topping.
  7. Transfer dough to prepared pan. Using slightly damp hands, press dough into an even layer (about ¾ inch thick). Press reserved M&Ms into top.
  8. Bake for 20-24 minutes, until edges are golden and center looks slightly underdone (soft and puffy, not wet). A toothpick should come out with moist crumbs.
  9. Cool in pan on a wire rack for 20 minutes. Use parchment overhang to lift slab onto cutting board. Cool completely (about 1 hour) before slicing into 24 bars.

Notes

Don’t overbake—bars continue baking in the pan after removal. Pull when center looks slightly underdone. Use processed peanut butter (not natural) for best texture. For gluten-free, use 1:1 gluten-free flour blend and certified gluten-free oats. Store in airtight container at room temperature for up to 5 days. Freeze for up to 3 months.

Nutrition

Keywords: monster cookie bars, M&M bars, soft baked cookie bars, peanut butter oatmeal bars, easy dessert recipe, 30-minute recipe, bar cookies

Find it online: https://merrymorsel.com/soft-baked-monster-cookie-bars-with-m-and-ms-easy-30-min-recipe/