2 cups all-purpose flour
1/2 cup sugar
2 teaspoons baking powder
8 tablespoons (1 stick) unsalted butter, melted and cooled
3/4 cup whole milk
1 egg, slightly beaten
1 teaspoon vanilla
1-1/2 cups fresh blueberries
1 heaping tablespoon sugar (optional, for tops)
Preheat the oven to 350 degrees F. Grease a 12-cup muffin pan. In a large bowl, combine the flour, sugar, and baking powder. Reserve one tablespoon of the mixture to coat the blueberries. In a smaller bowl, combine melted butter, milk, egg, and vanilla, and mix well. Add the milk mixture to the flour mixture and stir with a spatula or whisk until just blended (the batter can be lumpy). Do not over-mix or your muffins will be too dense. Toss the blueberries with the reserved flour mixture and gently fold the blueberries into the batter.
Fill muffin cups 2/3 full. Sprinkle tops with additional sugar, if desired. Bake for 20 to 25 minutes. Cool the muffins for 15 minutes before removing them from the pan.