Start by whisking together the dry ingredients — flour, sugar, baking powder, and salt — in a large bowl.
In another bowl, whisk the oil, egg, milk, and vanilla until smooth. Slowly combine the wet and dry ingredients, stirring gently with a spatula.
Once the batter is just combined, gently fold in the blueberries. If you’re using frozen blueberries, don’t thaw them first — just toss them straight in.
Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners. Divide the batter evenly among 12 cups, filling each about two-thirds full.
If you like a bakery-style finish, sprinkle the tops with coarse sugar before baking.
Bake for 18–22 minutes, or until the tops are golden and a toothpick inserted in the center comes out clean
Let the muffins cool in the pan for 5 minutes before transferring them to a wire rack.
