Sift together flour, baking powder, sugar, and salt. (Do not skip this step; you do not want lumpy pancakes.)
In a separate bowl, whisk together the egg, milk, and butter. Add the wet ingredients to the flour mixture and stir just until incorporated. (If the batter seems too thick to pour, add a little more milk.)
Spray a nonstick skillet or griddle with cooking spray and heat over medium heat, about 300°F.
When hot, pour ⅓ cup of batter into the skillet. Spread the batter out more, if necessary, to about a 4-inch diameter.
Working in batches, being careful not to overcrowd the skillet or griddle, cook the pancakes for 3-4 minutes, or until the bubbles begin popping on top of the pancake and they are golden brown on the bottom.
Gently, but quickly, flip over the pancakes. Cook an additional 3-4 minutes until the other side is also golden brown.
Wipe out the pan with a paper towel, and repeat with the remaining pancake batter.
Serve warm, topped with maple syrup.