Spray 12 cup muffin pan with nonstick spray. Preheat the oven to 375°F.
In a large bowl, whisk together flour, baking powder, and salt. In a separate bowl, whisk together yogurt, sugar, butter, eggs and maple flavoring. In a third bowl, toss rinsed blueberries with 2 tablespoons flour and 2 tablespoons sugar, until coated.
Use a rubber spatula to fold wet ingredients into dry, just until flour is barely visible. Don't over-mix (the batter will be lumpy). Gently fold in the coated blueberries.
Fill muffin cups using ½ cup batter in each. If desired, sprinkle each with coarse sugar.
Bake for 20 to 25 minutes, or until toothpick inserted in center comes out clean. Let sit for 5 minutes; remove to rack to cool completely.