With a mixer, cream together sugar and softened butter until fluffy. Add eggs one at a time, mix until blended. Add dry ingredients, mixing with milk alternately. Wash blueberries and pat dry. Sprinkle with alittle flour so they won't sink to the bottom of the muffin. Fold in blueberries. Grease cupcake tins with butter. Fill 3/4 full. Sprinkle sugar on top.
Bake in 375 degree oven for 20-25 minutes. Allow to cool completely before you pull them from the tin. Use paper tin liners if you want. It should make 10-12 muffins depending on the size muffin tin. Enjoy!