Frosted Orange Rolls

Ingredients:

1 package active dry yeast
¾ cup warm water
1½ cups warm milk
½ cup sugar, divided
1½ teaspoons salt
4½ cups flour, divided
¼ cup shortening, melted
For the orange icing:
4½ tablespoons butter, softened
1½ tablespoons orange zest
3 tablespoons orange juice
2¼ cups powdered sugar