Preheat the oven to 375°F.
Beat together the butter and sugar until well combined.
Add the eggs one at a time, scraping the sides and bottom of the bowl and beating well after each.
Add the baking powder, salt, and vanilla.
Add the flour alternately with the milk, beating gently just to combine. Scrape the bottom and sides of the bowl.
Add the blueberries to the batter, stirring until just combined. Be careful not to overmix or the muffins will be dense.
Scoop the batter by the heaping ¼-cupful into a greased (or paper-lined) 12-cup muffin pan.
Sprinkle about 1 teaspoon of granulated sugar over each muffin.
Bake the muffins for about 25 to 30 minutes.
