Description
Thick, chewy Monster Cookie Bars loaded with peanut butter, oats, M&M’s, and chocolate chips. Perfect for a crowd-pleasing treat that’s easy to make and irresistibly gooey in the center.
Ingredients
1/2 cup unsalted butter, melted
3/4 cup creamy peanut butter (Jif or Skippy recommended)
3/4 cup brown sugar, packed
1/2 cup granulated sugar
2 large eggs + 1 egg yolk
2 teaspoons vanilla extract
1 1/2 cups old-fashioned rolled oats
1 cup all-purpose flour
1 teaspoon baking soda
1/2 teaspoon salt
1 cup M&M’s
1/2 cup chocolate chips
Instructions
1. Preheat oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving overhang for easy removal.
2. In a large bowl, whisk together melted butter, peanut butter, brown sugar, and granulated sugar until smooth and glossy. Add eggs, extra yolk, and vanilla; whisk until fully combined.
3. Add oats, flour, baking soda, and salt. Fold gently with a spatula until just combined, leaving a few streaks of flour.
4. Fold in M&M’s and chocolate chips, reserving a small handful of each for topping.
5. Spread dough evenly in the prepared pan. Press reserved candies and chips on top.
6. Bake 20–25 minutes, until edges are set and lightly golden but center still looks soft.
7. Cool completely in pan before lifting out with parchment and cutting into bars.
Notes
For the chewiest texture, avoid overbaking – the center should look slightly underdone when you pull it from the oven.
Customize mix-ins by swapping in peanut butter chips, white chocolate chips, or chopped nuts.
Store bars in an airtight container at room temperature for up to 5 days, or freeze for up to 2 months.
- Prep Time: 15 minutes
- Cook Time: 25 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American