Line a square 8x8 baking pan with parchment paper. Preheat the oven to 350 F/180 C.
Melt the butter. Let it cool until still warm but not hot, about 5 minutes.
Whisk in the sugar and brown sugar.
Whisk in the peanut butter, egg, and vanilla.
Fold in the flour, baking powder, salt, and chocolate chips.
Spread the dough evenly into pan.
Press the nutter butter cookies into the top of the dough.
Bake at 350 for 25-27 minutes or until the edges are golden brown and wrinkled.