In a medium bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
In a separate bowl, whisk together the milk, egg, melted butter, and vanilla extract (if using).
Add the wet ingredients to the dry ingredients and whisk until just combined. Do not overmix. The batter will be lumpy, and that's okay.
Heat a non-stick skillet or griddle over medium-high heat. Spray with cooking spray or melt a small amount of butter in the pan.
Use a 1/4 cup measuring cup to scoop the batter into the skillet for each pancake. Cook until bubbles form on the surface and the edges are set, about 2-3 minutes.
Flip the pancake and cook until the other side is golden brown, about 1-2 minutes.
Repeat with the remaining batter, spraying the skillet with more cooking spray or adding more butter as needed.
Serve the pancakes warm with your favorite toppings, such as butter, syrup, fruit, or whipped cream. Enjoy!