Soft-Baked Monster Cookie Bars

Top view of a stack of cookie bars with a bite taken out of the top bar.

Soft-baked, thick, and chewy Monster Cookie Bars are an easy dessert recipe made in a 9x13 baking pan. Monster cookie bars are loaded with oats, peanut butter, chocolate chips, peanut butter chips, and m&m's for the best cookie bars ever!

Course Dessert

Cuisine American

Keyword monster cookie bars

Prep Time 10

Cook Time 14

Cooling Time 15

Total Time 39

Servings

Calories 248kcal

Author Jessica

Equipment

9x13 Pan

Ingredients

1½ cups all-purpose flour
1 cup quick oats
¾ teaspoon baking soda
¼ teaspoon salt
1/2 cup butter softened
1/3 cup creamy peanut butter not all natural
1/2 cup granulated sugar
1/2 cup packed light brown sugar
1 teaspoon vanilla extract
1 large egg
1 large egg yolk (discard the whites, only use the yolk)
1/2 cup peanut butter chips
1/2 cup miniature semi-sweet chocolate chips
1/2 cup mini m&m's

Instructions

Preheat the oven to 350℉. Lightly spray a 9x13-inch baking pan with cooking spray or line with parchment paper.
^{*I prefer using parchment paper because then you can lift the bars out for even cutting and slicing.}
In a small mixing bowl, whisk together the all-purpose flour, quick oats, baking soda, and salt. Set aside.
1½ cups all-purpose flour, 1 cup quick oats, ¾ teaspoon baking soda, ¼ teaspoon salt
In a separate larger bowl using a hand mixer, or use a stand mixer with the paddle attachment, beat together the butter, peanut butter, sugar, and brown sugar until it's fluffy, combined well, and much lighter in color; about 2 minutes of beating on medium speed.
1/2 cup butter, 1/3 cup creamy peanut butter, 1/2 cup granulated sugar, 1/2 cup packed light brown sugar
Add in the vanilla extract, egg, and egg yolk. Beat just until combined.
1 teaspoon vanilla extract, 1 large egg, 1 large egg yolk
Add the dry ingredients, peanut butter chips, mini chocolate chips, and mini m&m's into the larger bowl of wet ingredients. Beat on low speed just until combined well.
1/2 cup peanut butter chips, 1/2 cup miniature semi-sweet chocolate chips, 1/2 cup mini m&m's
Dump the monster cookie bar dough into the prepared pan and gently press it into the pan in an even layer; don't pack it too firmly into the pan, use a gently hand to spread it out evenly.
*If wanted, add a few extra mini m&m's and mini chocolate chips on top of the bars for a pretty look.
Bake for 12-16 minutes. The bars should be very lightly pale brown on the edges, while the center should still be pale and look slightly underdone.
^{*It's important to not over-bake the bars because as they cool in the warm pan, they will continue baking and set up perfectly soft.}
Let the bars cool, inside the warm pan at room temperature, for about 20 minutes. Cut into squares and enjoy warm or at room temperature.

Notes

Don't Over-Bake : This may seem obvious, but for this recipe in particular, it's so easy to think they're not done baking so you leave them in the oven longer than you should. I have never cooked these bars for longer than 13 minutes! Only the edges should have a very pale lightly golden brown color to them, while the center should still look pale and somewhat not fully cooked yet. I promise, as the bars set and cool down at room temperature, they will finish baking perfectly for that ultra soft-baked texture. When you take the bars out of the oven, there should be no golden brown color on them at all (just the very outer edges if anything). If the top of the bars are golden brown or lightly golden brown, chances are they have been over baked.

Use Mini Chocolate Chips & Mini M&M's : I know it may not seem important, but using the mini sized chips and m&m's allows for them to be more evenly dispersed in the cookie bars; which means you get everything in each bite. The mini version of chocolate chips are easy to find at most grocery stores.

Nutrition