Mix the butter, sugars, and vanilla. In a large bowl, add the melted butter, granulated sugar, brown sugar, and vanilla. Use an electric hand mixer or whisk to combine everything together for about 1 minute.
Fill the muffin tin. Line the muffin tins with cupcake liners. Then fully fill each of the prepared muffin cups with batter. You should get 12-13 muffins from this recipe.