Combine flour, baking powder, sugar, soda, and salt in a large mixing bowl. Grate in the butter. (Or you can cut it in with a pastry blender.)
Stir in cheese, bacon, and green onions if desired. Add buttermilk and stir lightly till just moistened. Drop by large spoonfuls onto a greased cookie sheet.
Bake at 425° for 15-17 minutes. Brush with melted butter while still hot.