1 cup granulated sugar
1 rounded tablespoon of cornstarch
Place them into a blender (or mason jar bullet) and process it at medium speed.
Let it process for about 30 seconds, stop and stir it, scraping the sugar off the sides. Repeat until powdered.
There is a difference in blenders, some make very smooth powder & some do not. It is NOT recommended to double the recipe. If you need more than one cup of sugar, repeat the process for each new cup. Doubling the recipe will cause it to FAIL.