Powdered sugar or confectioners sugar is made from granulated sugar. The granulated sugar is merely ground down or crushed until it becomes a very fine powder. You can make powdered sugar at home. For every cup of powdered sugar you need, you will simply put 1 cup of granulated sugar into a blender and blend at the highest speed until it forms a light powder. You will want to use it right away or else put it in an airtight container. If you want to prevent caking or increase it’s thickening, add 1 to 2 tablespoons of cornstarch per cup of powdered sugar.