Beat butter, 1/2 cup sugar, and egg at medium speed with a mixer until creamy and well blended.
Combine flour and next 3 ingredients; add to butter mixture alternately with milk, beginning and ending with flour mixture. Beat at low speed until blended after each addition. Spoon into greased miniature (1 3/4-inch) muffin pans, filling two-thirds full.
Bake at 350° for 14 to 16 minutes. Remove from pans immediately.
Combine 1/4 cup sugar and cinnamon. Dip tops of muffins in 2 tablespoons melted butter and then in sugar mixture.
Note: Batter may be baked in regular muffin pans for 20 to 25 minutes.