In another bowl, whisk the milk, egg, and melted butter until combined. Pour the wet ingredients into the dry ingredients and stir just until combined; do not overmix—some lumps are okay. Let the batter rest for 5 minutes while you heat a nonstick skillet or griddle over medium heat. Lightly grease the pan with butter or oil. Pour 1/4 cup of batter for each pancake onto the skillet. Cook until bubbles form on the surface and the edges look set, about 2–3 minutes. Flip and cook the other side for 1–2 minutes until golden brown and cooked through. Repeat with the remaining batter. Serve warm with maple syrup, fruit, or your favorite toppings.