Preheat the oven to 350°F and either grease your mini muffin tin or line it with mini paper liners.
To make the batter, whisk the flour with the baking powder, baking soda, and salt in one bowl. In another bowl, stir together the butter with the sugars, then add eggs, milk, and vanilla. Add the dry ingredients to the wet ingredients and stir until just combined.
Gently fold in the blueberries.
Pour the batter into the prepared mini muffin tin.
Bake at 350°F for 12-13 minutes. Let cool slightly in the pan, then remove to a wire rack to cool completely.
Notes
These muffins will store great in an airtight container for three days at room temperature or three months in the freezer!