Measure flour, sugar, baking powder, and salt into bowl.
Mix the eggs, milk, and vanilla together. Gradually whisk these ingredients into the bowl with the flour mixture.
Add the melted - and cooled - butter and whisk into the mixture.
The mixture should be about the consistency of syrup. If it seems a little thick, add more milk until you get the correct consistency.
Let the batter stand at least ten minutes to allow the flour to thicken.
For each crêpe, lightly spray a non-stick medium-sized frying pan with cooking spray. Pour about a quarter cup of the batter into the skillet; immediately rotate the pan until the batter covers the bottom. Cook until light brown; flip with a spatula and brown on the other side.
If the crêpe seems too thick, then add additional milk to the crêpe batter.
When removing the crépe from the frying pan, stack it so that the first-baked side is down. Cool, keeping the crêpes covered to prevent them from drying out. After each three crêpes, place a layer of waxed paper to separate them. If you are using them that day, leave them on the counter with the top crêpe covered with wax paper. To use another day, put the crêpes in a zippered bag and store in the refrigerator.
