Preheat oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or grease thoroughly. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside. Toss the fresh blueberries with 1 tablespoon of flour to prevent them from sinking to the bottom of the muffins.

In a large mixing bowl, beat the softened butter and sugar together until light and fluffy, about 2-3 minutes. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

Add the flour mixture to the butter mixture in three additions, alternating with the milk. Begin and end with the flour mixture. Mix until just combined - do not overmix! Gently fold in the flour-coated blueberries, being careful not to crush them.

Divide the batter evenly among the 12 muffin cups, filling them almost to the top. For that professional bakery look, sprinkle with coarse sugar if desired. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean. The tops should be golden brown and spring back when lightly touched.

Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely. Serve warm or at room temperature.