Place self-rising flour in a medium mixing bowl. Cut in 1 cup butter with a pastry blender until mixture resembles coarse meal. Gradually add sour cream, stirring just until dry ingredients are moistened.
Spoon batter into lightly greased miniature muffin pans, filling two-thirds full. Bake at 400° for 20 minutes or until lightly browned. Serve warm with additional butter.