Preheat the oven to 400°F. Fill a 12-cup muffin tin with parchment paper liners. In a large bowl, stir together the flour, sugar, baking powder, and salt. In another bowl, whisk the milk with the egg, melted butter, and vanilla until well combined. Pour into the dry ingredients and mix until just incorporated but a few lumps remain. With a spatula, gently fold in the blueberries.

Divide the batter evenly into the muffin tins, using a ¼ cup ice cream scoop if you’d like. Bake until muffins are golden brown and a toothpick inserted in muffins comes batter-free, with some blueberry stains, about 18 minutes. Cool on a rack and serve warm. Muffins will taste best eaten the same day.