This is kind of ironic as we once needed some powered sugar and the local store was out since it was a “seasonal” item – lol! If I had only known about how to make it myself, this would have been great! Many people suggest adding a tablespoon of corn starch to a cup of sugar to add a little flavor and aid in anti-clumping. Details from Lifehacker:
If you ever need powdered sugar and don’t have any on hand you can make it yourself by blending regular granulated sugar in a blender for a minute or two.
Last night my wife decided to use up leftover lemons by making lemon bars, but we were out of powdered sugar to dust the bars. Fortunately natural household weblog Keeper of the Home shared the tip on their page for making unrefined powdered sugar. The authors of that weblog use naturally-produced sugars such as Sucanat or Rapadura but rest assured that the technique works equally well with plain white granulated sugar.
If you have a smaller or less-powerful blender you won’t want to make more than a cup at a time as the weight of the sugar will pack down the blades and overwork the blender motor. Even if you have a Vita-Mix or other performance blender you will still only want to make a maximum of two cups in a single batch. In our Magic Bullet we made a half cup by blending for 45 seconds or so. Also keep in mind that blending sugar could scratch a plastic blending jar—I didn’t notice any scratching on our Magic Bullet, but it might scratch with repeated use.
If you compare the cost per ounce of powdered sugar to granulated sugar you might find it worth your time to forget commercial powdered sugar and make it yourself as needed.
How to Make Your Own (Unrefined) Powdered Sugar | Keeper of the Home