Blueberry Muffins

I think this is my favorite muffin recipe. I found it on a bread and breakfast website for Admiral's Quarters Inn in Maine.

2 1/2 cups blueberries (frozen or fresh)
1/2 cup butter
1 cup sugar
2 eggs
2 cups flour
2 teaspoons baking powder
1/2 teaspoon salt
1 teaspoon vanilla
1/2 cup milk
2 teaspoons and 1 teaspoon cinnamon for tops

Cream Butter and sugar. Add eggs one at a time and blend. Add dry ingredients alternately with milk and vanilla. Add blueberries and stir by hand. Grease muffin tins well, pile mixture high in muffin tin, and sprinkle tops with sugar and cinnamon. Bake at 375 degrees for 30 minutes. Cool.