Sift together flour, baking powder, sugar, and salt in a large bowl.

Whisk milk and egg together in a small bowl; whisk into flour mixture until blended. Stir in melted butter and lemon zest.

Heat a lightly oiled griddle over medium-high heat. Drop batter by 1/4 cupfuls onto the griddle; drop a few blueberries on top, then cover each with a little more batter. Cook until bubbles form and the edges are dry, 3 to 4 minutes. Flip and cook until browned on the other side, 2 to 3 minutes. Repeat with remaining batter.