In a small bowl, dissolve yeast in warm water and set aside. In a large bowl mix milk, melted butter, sugar, salt and egg. Add 2 cups of flour and mix until smooth. Add yeast mixture. Mix in remaining flour until dough is easy to handle. Knead dough on lightly floured surface for 7 to 10 minutes. Place in well-greased bowl, cover and let rise until doubled in size, normally 1 1/2 hours.
When doubled in size. Roll out on a floured surface into a 15 by 9-inch rectangle. Spread melted butter all over dough.
Mix sugar and cinnamon and sprinkle over buttered dough. Sprinkle with walnuts, pecans, or raisins if desired.
Place cinnamon roll slices close together in the pan and let rise until dough is doubled, about 45 minutes.
Bake for about 30 minutes. Mix butter, powdered sugar, and vanilla. Add hot water 1 tablespoon at a time until the glaze reaches desired consistency. Spread over slightly cooled rolls.