1. Beat egg whites and cream of tartar in a small bowl, until foamy.
2. Slowly beat in 10X sugar until frosting stands in firm peaks and is stiff enough to hold a sharp line when cut through with a knife. (Keep bowl of frosting covered with damp paper toweling while working, to keep frosting from drying out. Store any leftover frosting in a tightly covered jar in the refirgerator for another day's baking.)