Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.
In a large bowl, combine the flour, baking powder, salt, and sugar.
In another bowl, whisk together the melted butter, eggs, milk, and vanilla extract.
Pour the wet ingredients into the dry ingredients and mix until just combined.
Gently fold in the blueberries, being careful not to overmix.
Spoon the batter into the prepared muffin tin, filling each liner about 2/3 full.
Bake for 20-25 minutes, or until a toothpick inserted comes out clean.
Remove from the oven and let cool in the pan for 5 minutes.
Transfer muffins to a wire rack to cool completely.
Enjoy your freshly baked blueberry muffins!