Preheat the oven to 350 F. Lightly grease the bottom of a baking pan and line it with parchment paper. Set it aside.

In a medium mixing bowl, combine the flour, baking powder, and baking soda. Set aside.

In a large mixing bowl using a hand mixer on medium-high speed, cream the butter and both sugars together.

Add in the eggs, vanilla, and salt and mix on medium speed until just incorporated.

Slowly add the flour mixture and mix until you get a cookie dough consistency. Then fold in 1 cup chopped Reese’s peanut butter cup minis, ¾ cup semisweet chocolate chips, and ¼ cup chopped walnuts until evenly distributed in the dough. Set the remaining aside for topping.

Spread and press the cookie dough down into an even layer in the prepared baking pan. Sprinkle on the remaining toppings and lightly press them in so they stay in place.

Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

After baking, leave the bars in the pan and set it on a wire rack. Allow it to cool at room temperature before cutting into squares and serving.