Mix yeast with warm milk. Let sit five minutes.
Combine flour, sugar, and salt in large bowl.
Add yeast mixture, melted butter, and egg.
Knead dough until smooth. About eight minutes total.
Place in greased bowl. Cover with towel.
Let rise one hour until doubled in size.
Roll dough into rectangle on floured surface.
Spread softened butter evenly across dough surface.
Mix brown sugar and cinnamon in bowl.
Sprinkle cinnamon mixture over buttered dough evenly.
Roll dough tightly from long side into log.
Cut into twelve equal slices with knife.
Place rolls in greased baking dish. Space apart.
Let rise thirty minutes until puffy and doubled.
Bake at 375°F for twenty-five minutes total.
Mix powdered sugar, milk, and vanilla for glaze.
Pour glaze over warm rolls before serving immediately.