Preheat oven to 350 degrees. Line muffin tins with fun cupcake liners.
Sift together 2 cups flour, baking powder, 1/2 cup sugar and salt in a mixing bowl, set aside.
In a small bowl, toss together blueberries with 2 tablespoons flour and 2 tablespoons sugar. Set aside.
In a stand mixer fitted with the paddle attachment or a large mixing bowl with an electric mixer, blend melted butter, milk and egg.
Slowly add dry ingredients to the batter. Do not over mix. Stop when it is combined, but there are still small lumps.
Fold in blueberries. The batter will marbleize or turn blue if using frozen blueberries. Don't panic.
If using the sugar topping, mix both sugars in a small bowl.
Fill muffin tins 2/3 full. Sprinkle tops evenly with sugar mixture.
Bake for 25 minutes for large muffins and 18 minutes for small muffins. Times may vary based on oven and how much you filled those cups (I know a few of you took some chances and filled them to the brim, didn't you??). Muffin tops will spring back to the touch.