Preheat oven to 350°F. Line an 8x8-inch pan with foil and spray with nonstick cooking spray.

Place melted butter in a large bowl. You just need a wooden spoon to mix these! Add granulated and brown sugars and stir until the mixture is smooth. Stir in egg and vanilla extract.

Stir in cocoa, baking soda, and salt, then slowly mix in flour and mix just until the batter is smooth and comes together. Be sure to scrape the sides of the bow. Slowly stir in chocolate chips.

Press half of cookie dough in the bottom of the prepared pan. Layer will be thin. If it sticks to your hands spray them with nonstick cooking spray so they don’t stick, or press them down with a spatula.

Place peanut butter in a medium microwave-safe bowl. Heat for 45 seconds, or until it’s smooth and liquid. Whisk in the powdered sugar, vanilla, and milk. Switch to a wooden spoon or spatula and stir until combined. Mixture will be thick. Spread over cookie layer leaving a small border around the edges.

Use your hands to press the remaining cookie dough on top of the peanut butter layer, being sure to seal the edges. There will be just enough cookie dough for a thin layer.

Bake for 28-33 minutes or until the top looks no longer glossy. Cool completely before slicing into bars.

Store in an airtight container for up to 3 days or freeze for up to 2 months.