Preheat your skillet or griddle: Place it over medium heat. It's ready when a drop of water sizzles and evaporates immediately.
Mix dry ingredients: In a large bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
Mix wet ingredients: In another bowl, whisk together the milk, melted butter or oil, egg, and vanilla extract (if using).
Combine wet and dry ingredients: Pour the wet ingredients into the dry ingredients and stir until just combined. It's okay if there are some lumps; overmixing can result in tough pancakes.
Grease the skillet or griddle: Lightly grease it with butter or oil. You can also use cooking spray.
Cook the pancakes: Pour about 1/4 cup of batter onto the skillet for each pancake. Cook until bubbles form on the surface and the edges look set, about 2-3 minutes.
Flip the pancakes: Once bubbles have formed and the edges look set, carefully flip the pancakes with a spatula and cook for another 1-2 minutes, or until golden brown on the bottom.