In a large bowl, combine flour, sugar, baking powder, baking soda, and salt.
Make a well in the center and add milk, melted butter, vanilla, and egg.
Whisk the wet ingredients first, then gently fold into the dry ingredients until just combined.
The Best Fluffy Pancakes batter should be thick and slightly lumpy. If too thick, add milk gradually.
Let the batter rest while heating a nonstick pan over low-medium heat.
Lightly grease the pan with butter.
Pour 1/4 cup batter onto the pan and gently spread into a circle.
Cook until bubbles form and the bottom is golden, then flip and cook the other side.
Repeat with remaining batter and serve warm.