Cream butter, brown sugar, and peanut butter together until creamy. Add in eggs, vanilla, and salt. Combine flour and baking powder with dough and continue mixing for another 30 seconds, dry ingredients are mixed in with the dough. Using a rubber spatula, spread the dough mixture into a lightly sprayed 13x9-inch baking pan.
Bake for 18-20 minutes, or until the dough sets. (It will begin to turn golden brown).
Remove from the oven and allow to cool before frosting.
For the frosting and topping
In a medium bowl, cream powdered sugar, cocoa powder, and butter. Add in vanilla and water. Mix until all ingredients are well combined and frosting will be smooth and creamy. If the frosting is too thick, add a teaspoon of water to thin. Use a rubber spatula to frost bars.
Cut bars into squares. Serve.
Notes
If desired, top with Reese’s pieces, chopped peanut butter cups, M&M’s candies, or chocolate chips.
Frosting and toppings are not needed. These bars are delicious by themselves.
If using salted butter, you could omit the salt from the recipe, or lower it to just a pinch.
I have never made this recipe with crunchy peanut butter because my family likes smooth cookies, but I would imagine it would also work.