Preheat the oven to 350℉. Line 2 cookie sheets with parchment paper and set aside.
Add the softened butter, granulated sugar and powdered sugar to the bowl of a stand mixer. Beat with a flat beater attachment on high speed for 3 minutes, or until pale and creamy.
Add the egg, vegetable oil, vanilla extract and almond extract to the butter mixture. Beat on a medium speed until well combined, scraping the sides of the bowl with a spatula as necessary.
Add the flour, cornstarch, baking powder and salt to the stand mixer. Beat on a low speed until just combined.
Use a cookie scoop to scoop spoonfuls of dough. Roll the dough into a ball that's about 3" wide and about ½ thick, then place on the lined cookie sheet and flatten down gently with the base of a drinking glass.
Bake the cookies for 8-9 minutes or until only just beginning to color. Allow to cool for 5 minutes on the cookie sheets before transferring to a cooling rack to cool completely.
To make the frosting, beat the butter in the bowl of a stand mixer using a wire whisk attachment until pale and creamy. Add the milk, vanilla extract, salt and food coloring (if using), and beat on a medium speed until well combined, scraping the sides of the bowl as necessary.
Add the powdered sugar, 1 cup at a time, and beat on a low speed until well combined before adding the next cup. Turn the speed up to high and beat for 1 minute or until thick and fluffy.
Spread the frosting over the cooled cookies with an offset spatula or butter knife then decorate with the sprinkles, if using.