Add yeast and sugar to warm water, mix and let sit for 6-8 minutes. Mix together milk, butter, sugar, salt and yeast. Add in flour, 1/2 cup at a time, until dough becomes smooth and forms a ball. Dough will be slightly tacky. Spray a large glass bowl with cooking spray. Place dough in the bowl, cover, and let rise until double in size (about 30 minutes). Roll out dough into an 8X12 in. rectangle and cut to make 12 rolls. Roll each piece into a ball and place on a greased baking sheet. Loosely cover with plastic wrap and let rise for 30 minutes. Pre-heat oven to 350F. Bake rolls for 20-25 minutes or until golden brown. Brush with melted butter if desired. Serve warm.
