Combine the flour, peanuts, chocolate, baking powder and salt in a stainless steel bowl.
With an electric mixer, cream the brown sugar and butter together until smooth. Add the eggs one at a time, making sure to completely incorporate each egg before adding the next. Beat in the vanilla. Using a rubber spatula, add the peanut butter and stir until smooth. Stir in the flour and peanut mixture and stir until just combined.
Form the dough into balls the size of golf balls and place on a parchment-lined baking sheet, leaving about 2 inches between each cookie. Bake until the cookies are set but still have soft centers, 10 to 12 minutes. Cool on the baking sheet until they are slightly above room temperature, about 10 minutes. Using an offset spatula, transfer the cookies to a wire rack to cool completely.
Using a fine-mesh strainer, sprinkle half of the cookies with cocoa powder and the other half with confectioners' sugar.
Some people have allergies to peanuts, and if serving to guests, please make them aware of the inclusion of this peanut product.