Add the baking powder and salt to the wings. Stir to coat.
Spray a baking rack with nonstick cooking spray and place on top of a foiled sheet pan. Distribute wings evenly on top, making sure none of them touch and they are all face-up.
Bake for 35 minutes, then increase the temperature to 425˚F (220˚C) and bake for an additional 45 minutes, or until wings are crisp and golden. (Do not remove the wings from the oven when increasing temperature.)
For sauce, in a hot pan, melt butter. Add lemon juice, pepper, and salt. Stir until combined.