In a mixing bowl, cream butter and sugar. Add eggs, buttermilk and vanilla; mix well. Combine flour, baking soda, baking powder and salt; stir into the creamed mixture just until moistened.

Fold in blueberries (batter will be thick). Fill greased or paper-lined miniature muffin cups with about a tablespoon of batter. Sprinkle with sugar if desired.

Bake at 400° for 10-15 minutes or until muffins test done. Cool for 5 minutes before removing from pan to a wire rack.

Yield: 7 dozen.