Preheat oven to 375°F.
In a large mixing bowl, cream together butter and sugar until light and fluffy; add eggs, one at a time, beating after each addition.
In a second bowl, combine all dry ingredients. (You can use an electric mixer to combine the dry ingredients thoroughly at this point so that you won't need to overmix once the wet and dry ingredients are combined.
Gradually add the dry ingredients to the creamed butter and sugar mixture along with the milk and vanilla.
Optionally, mash ½ cup of the blueberries, and stir in by hand (this will turn batter a light shade of blue and add a touch of blueberry flavor, but this step may be skipped, if you wish). Add the remaining whole berries and stir in gently by hand.
Spray a 12 muffin baking pan with Baker's Joy (or other non-stick spray). Fill greased muffin cups.
Sprinkle sugar on top of unbaked muffins.
Bake at 375°F for 25-30 minutes. Cool in pan. Run a knife around the edge of each muffin after several minutes to free it from the pan and cool on wire racks. Muffins may be brushed with melted butter and sprinkled with sugar, if desired.