Dissolve yeast in warm water; set aside.
Combine butter, sugar, and egg in a large mixing bowl; beat until well blended. Add yeast mixture; mix well. Stir in flour to make a soft dough.
Spoon batter into well-greased muffin pans, filling two-thirds full. Bake at 350° for 25 minutes or until lightly browned.
Note: Batter may be refrigerated for several days in an airtight container.