In a bowl, cream butter and sugar. Add eggs, buttermilk and vanilla; mix well.

In a seperate bowl 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 a toothpick inserted in muffin comes out clean.