1 1/2 cups of sugar
1 egg yolk
2 teaspoons vanilla
3 cups flour
1 1/4 teaspoons baking soda
1/2 teaspoon cream of tartar
1 teaspoon cornstarch
1/2 teaspoon salt
1 cup sprinkles
Frosting: 3/4 cup butter, room temp
2 1/4 cup confectioner’s sugar
3 tablespoons heavy cream
1 teaspoon vanilla
1/8 teaspoon salt
With an electric mixer, cream the butte and sugar until light, about 2 mins. Add egg, egg yolk, and vanilla. Scrape bowl as needed.
In a separate bowl, whisk together the flour, baking soda, cream of tartar, cornstarch, and salt. Slowly add to the butter mixture on low speed and mix until combined. Gently mix in the sprinkles by hand. Cover and chill for at least 3 hours.
Remove from the fridge and preheat oven to 325. Let cookies sit at room temperature for 15 minutes unless you have chilled them overnight. If so, let them sit for about 30-40 minutes.
Form dough into balls. Bake for 9-10 minutes until the edges are slightly browned. The centers will appear soft. Allow to cool on pan for 3 minutes then transfer to wire rack to cool. They need to be completely chilled before you frost them.
Frosting: With a hand mixer, beat the butter until creamy. Add confectioners’ sugar, cream, vanilla, and salt and mix on low speed until combined then increase the speed and mix for about 3 minutes. Add more sugar or cream if too thick or thin.
Place as much frosting as you like on the cookies and then finish with sprinkles.