Sift together flour, baking powder, salt, and sugar in a large bowl.
Whisk in melted butter, egg, and milk until combined. Let batter rest for 5 minutes.
Preheat a large skillet over medium-high heat. Spray with cooking spray. Pour batter into the hot skillet, about 1/4 cup of batter for each pancake. Cook for 2 to 3 minutes, until bubbles appear on the sides and center of each pancake. Flip and cook until golden, about 1 to 2 minutes.