Preheat the oven to 350°F (175°C)
Line a muffin tin with cupcake liners
Mix flour, sugar, baking powder, and salt in a bowl
In another bowl, whisk eggs, milk, melted butter, and vanilla
Combine the wet and dry ingredients until just mixed
Fill each liner about two-thirds full with batter
Bake for 18 to 22 minutes
Check doneness with a toothpick
Remove from the oven and let cool
Frost or decorate after cooling