• Preheat the oven to 375 degrees.
• Place the vanilla extract, vegan butter and aquafaba in a bowl and beat with a hand mixer, or in a stand mixer, until fluffy, about a minute.
• Add in the confectioners sugar and mix it in.
• Add the two flours and mix in. Your dough should form at this stage. It will look a little dry but will hold together. If it doesn't come together at all, add a few drops of aquafaba until it does, but be careful-- it should not get sticky.
• Roll out the dough to ¼th-inch thickness on the countertop. Dust the countertop, if needed, with cornstarch but you should not really need to if your dough is at the right consistency.
• Cut out your cookies using a cookie cutter. Place them at least a couple of centimeters apart on a cookie sheet.
• Bake 7-8 minutes or until the cookies just start to brown. Do not overbake. Remove and let them cool for five minutes on the cookie sheet. Then, using a spatula, transfer to a rack to continue cooling.

Make the frosting:

• Place the sugar in a bowl with the butter, nondairy milk, and vanilla extract. Mix well with a fork, then beat with a hand mixer until fluffy and smooth.
• Use a knife or an offset spatula to frost your cookies. If you wish, add some natural food coloring, or add some sprinkles!