Separate rolls into eight triangles. Combine sugar and cinnamon. Dip each marshmallow into butter, roll in cinnamon-sugar and place on a triangle. Pinch dough around marshmallow, sealing all edges. Dip tops of dough into remaining butter and cinnamon-sugar. Place with sugar side up in greased muffin cups. Bake at 375° for 13 to 15 minutes. Serve warm.