Sift flour, baking powder, sugar, and salt together in a large bowl. Combine milk and egg in a small bowl. Stir egg mixture into flour mixture until just combined. Stir in melted butter, then fold in blueberries. For best results, set the batter aside for 1 hour.

Heat a lightly oiled griddle or nonstick frying pan over medium-high heat.

Pour or scoop the batter onto the hot griddle, using approximately 1/4 cup for each pancake; cook until bubbles appear on the surface, then flip and cook until golden brown on both sides. Serve hot.