How to make homemade confectioners sugar

So today I am going to make some Homemade Oreo Cookies, only to realize I don't have any Confectioners Sugar (AKA Icing Sugar)!

No worries my friends, I can make homemade icing sugar. SUPER EASY and much cheaper than the store bought sugar.

Ingredients

1 cup of regular white sugar for every 1 cup of icing sugar needed.
1 tbsp cornstarch for every cup of sugar (SEE NOTE)

Directions

Place a cup of granulated sugar in the blender for each cup of powdered sugar needed.
Blend at high speed until the sugar turns to powder.
Use right away, or store in an air-tight container.

Note:

To prevent caking and improve thickening ability (important when making icing), add 1-2 Tablespoons of corn starch for each cup of sugar made.

Sugar may etch your blender pitcher, particularly if it's made of plastic. If this is a concern, use a coffee grinder or spice grinder instead.