Preheat oven to 400° F.

Stir together flour, sugar, baking powder, baking soda, and salt. Make a well in the center of the dry ingredients.

In another bowl, whisk the egg and then whisk in the buttermilk, vanilla, and melted butter. Pour mixture all at once into dry ingredients. Quickly stir to partially blend. Add blueberries. Carefully fold together to moisten. The batter will be thick and lumpy. Spoon batter into 12 paper-lined muffin tins. The cups will be full. Sprinkle the tops with the 1 tablespoon sugar. Bake 25-30 minutes. When done, the tops will spring back when lightly touched. Let cool in the pan for 5 minutes and then carefully remove and cool on a rack.