Prep Oven and Pan:Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish or line it with parchment paper for easy removal.
Make the Crust:In a mixing bowl, stir together melted butter and graham cracker crumbs until evenly combined. Press this mixture firmly into the bottom of your prepared pan to form a solid crust layer.
Prepare Peanut Butter Layer:In a separate bowl, whisk the sweetened condensed milk, creamy peanut butter, and vanilla extract until smooth and well blended. Pour this mixture evenly over the graham cracker crust
Add Chocolate Toppings:Sprinkle chocolate chips, peanut butter chips, and halved mini peanut butter cups evenly over the peanut butter layer. Gently press them down to embed slightly into the filling.
Bake:Place the pan in the preheated oven and bake for 25 to 30 minutes. The edges should turn golden brown, and the center will look set but still slightly gooey.
Cool and Serve:Remove from oven and cool completely on a wire rack. Once cooled, slice into bars and serve. Enjoy your rich and gooey peanut butter cup cookie bars!
