Preheat oven to 325 degrees F. Line a large baking sheet with parchment paper and set aside.
Add butter and 1/3 cup powdered sugar to the bowl of a stand mixer. Cream until very light and fluffy, 4 to 5 minutes. Add vanilla extract and almond extract and mix.
Add flour, cornstarch and salt to the mixer and mix until just combined. Overmixing causes tough cookies. Stir in the sprinkles by hand.
Using a tablespoon measuring spoon, portion out the dough. Roll into balls and place 1 inch apart on the prepared baking sheet. Bake cookies for 16 to 18 minutes, until lightly golden. Remove from oven and allow to cool on baking sheet for a minute.
Place remaining 2/3 cup into a pie plate or cake pan. While still warm, roll the cookies in the powdered sugar. Place on a wire rack and allow to cool completely. Once cooled, give another generous roll in the powdered sugar. This second roll will give the cookies that perfect powdered sugar coating.