Monster Cookie Bars – Thick, Chewy, and Loaded with Goodies
Monster Cookie Bars combine the best parts of oatmeal cookies, peanut butter cookies, and candy-loaded treats into one thick, chewy, bake-sale-ready dessert. They’re easy to mix, even easier to eat, and guaranteed to disappear fast.
Equipment
- 9x13 inch baking pan Grease or line with parchment paper
- Large mixing bowl For wet ingredients
- Medium bowl For dry ingredients
- Hand or stand mixer Or mix by hand
- Spatula For folding and pressing dough
- cooling rack Optional, but helpful
Ingredients
- ½ cup unsalted butter, softened
- 1 cup brown sugar, packed
- ½ cup granulated sugar
- 1 cup creamy peanut butter
- 2 large eggs
- 2 teaspoons vanilla extract
- 1 ¼ cups all-purpose flour
- 1 cup old-fashioned rolled oats
- 1 teaspoon baking soda
- ½ teaspoon salt
- ¾ cup semi-sweet chocolate chips
- 1 cup M&M candies (plus extra for topping)
- **Optional Add-Ons:**
- ½ cup chopped nuts (peanuts, pecans, or walnuts)
- Extra chocolate chips or flaky sea salt, for topping
Instructions
- Preheat oven to 350°F (175°C). Lightly grease a 9×13-inch baking pan and line with parchment paper if desired.
- In a large bowl, beat softened butter, peanut butter, brown sugar, and granulated sugar together until light and fluffy (2–3 minutes).
- Beat in the eggs one at a time, then add vanilla. Mix until fully combined and smooth.
- In a separate bowl, whisk together flour, oats, baking soda, and salt.
- Gradually add dry ingredients to wet ingredients. Mix on low just until combined—don’t overmix.
- Stir in chocolate chips and M&Ms (and nuts, if using) until evenly distributed.
- Spread dough into the prepared pan and press into an even layer. Sprinkle extra candies or chips on top if desired.
- Bake for 22–28 minutes, until the edges are golden and the center is just set. Don’t overbake—the bars will firm up as they cool.
- Let cool in the pan for at least 30 minutes, then lift out (if using parchment) and slice into squares or rectangles.