When I looked at the ingredients, 4 cups of powdered sugar seemed like a lot for my dozen cinnamon rolls, so I cut the recipe in half. I ended up only using half of what I made. The rest is in the refrigerator. I plan to make another batch of Mattie's Sticky Cinnamon Rolls again soon, and I will use up the left over icing at that time.
Thanks for letting us know that the icing can last for two weeks in the fridge.