Preheat oven to 375ºC (175ºC) and line a 12-cup muffin pan with muffin/cupcake baking cups or spray with non-stick cooking spray.
In a large bowl, whisk together butter, eggs, vanilla and milk.
In another bowl, whisk together flour, sugar, baking powder and salt. Add blueberries and toss to coat.
Stir the berry mixture into the wet ingredients just until combined.
Divide the batter evenly among the cups and sprinkle the remaining teaspoon of sugar across the tops. Bake for 25-30 minutes until golden and a tester comes out clean. Let cool in pan for 5 minutes so the muffins are easy to remove then transfer to a wire cooling rack and enjoy!