Step 1

Preheat oven to 350°F. Line a 9x13 inch baking pan with foil, leaving about 1 inch of the foil extending over the edges of the pan. The extra foil will create handles that you can use to lift the Monster Cookie Bars from the pan. Spray foil with nonstick cooking spray. Set pan aside.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with an electric mixer, cream butter, peanut butter and sugars on medium speed for about 3 minutes. Add in vanilla and eggs and mix until combined.

Step 3

In a medium bowl, whisk together the flour, baking soda, salt and oats. Gradually add the dry ingredients into the butter mixture until thoroughly incorporated. Stir in chocolate chips and add-ins.

Step 4

Spoon batter into prepared pan and spread into an even layer. If desired, top batter with additional chocolate chips,  M&M’s or other add-ins, pressing them lightly into the batter. Bake in preheated oven for 30-35 minutes. If desired, sprinkle bars with flaky sea salt after removing from oven. Place pan on a cooling rack and cool completely before cutting into squares.