Preheat the oven to 350°F. Line a 13x9” metal baking pan with foil then grease the foil with cooking spray.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and brown sugar until light and fluffy, about 2 minutes. Add the vanilla extract and salt, then add the eggs one at a time, beating between each addition.
Add the flour and baking powder and beat just until combined then stir in the chopped peanuts and peanut butter chips.
Spread the batter into an even layer in the prepared baking dish then top it with additional chopped peanuts and peanut butter chips.
Bake the blondies for 28 to 30 minutes or until they are just set.
Remove them from the oven and allow them to cool completely in the pan before slicing and serving.