Funfetti Cut Out Sugar Cookies

1. Preheat oven to 350º F.
2. In a stand mixer fitted with a paddle attachment, blend together the butter and sugar on medium speed until light and fluffy. Scrape down the sides of the bowl.
3. Add in the egg and vanilla and mix until combined.
4. With the mixer on low, sift in the flour, cornstarch, and salt and mix just until combined, scraping down the sides of the bowl as needed. Gently fold in the sprinkles with a spatula, setting a small amount aside.
5. Flatten the dough into a disk, sprinkle the few remaining sprinkles right on top, and wrap in plastic wrap. Chill for 30 minutes.
6. Place a piece of parchment or a dough mat down and lightly flour it. Place the chilled dough on top, sprinkle some flour over it and roll it out until it is about ¼" thick. Sprinkle a little more flour where needed as you roll it out, making sure it isn't sticking to the parchment or mat that's under it.
7. Once the dough is rolled out, slide a cookie sheet under the mat or parchment and place it in the freezer for a few minutes or the fridge for 10 minutes. This will help firm up the dough again before you cut out any shapes.
8. Cut out all shapes and gently transfer them to a parchment lined baking sheet. Bake for 8-10 minutes depending on the cookie size. Let cookies cool for 10 minutes before moving to a cooling rack. Enjoy!