In a large bowl, or the bowl of a stand mixer, beat the butter and powdered sugar together until light and fluffy. You’ll want to beat this for at least 4 minutes, scraping down the sides of the bowl a few times. Add the vanilla and beat to combine.

In another bowl, whisk together the flour, cornstarch, and salt.

Add the dry ingredients to the mixer bowl and mix just until combined. The mixture will look crumbly, but the dough will stick together if you press on it.

Transfer the dough to the refrigerator and refrigerate for 2 hours.

Preheat the oven to 325ºF.

Once firm, roll the dough into balls about 1 1/2 tablespoons of dough each. (I used a small cookie scoop to keep them all the same size.) Place the balls on 2 baking sheets that have been lined with parchment paper or a silpat liner.

Press the tops of the cookies with a fork and sprinkle with a few sprinkles.

Place one cookie sheet in the oven and bake until the edges are just set, about 12 minutes. While the first tray is baking, place the second tray in the refrigerator.

Once baked, remove from the oven and bake the second tray.

Allow the cookies to cool on the baking tray.