In a large mixing bowl, combine flour, baking soda, cream of tartar, and salt. Mix until all ingredients are combined well and set aside.

In a separate mixing bowl, cream together the butter and sugar using an electric mixer. Mix until smooth.

Add in egg and vanilla and continue to mix until well combined.

All flour mixture to butter mixer and mix for about 2 minutes until the dough forms. It will be crumbly at first.

Mix in half of your sprinkles until they are evenly distributed throughout the dough.

Cover and place inside the refrigerator for 2 hours or overnight to chill.

When you’re ready to bake the cookies, preheat the oven to 350 degrees and prepare a large cookie sheet with parchment paper.

Using a 1 inch cookie scoop, scoop dough from bowl and form into an even, smooth, round ball using the palms of your hands.

Dip one side of the ball down into the remaining sprinkles and place on parchment paper, sprinkle side up. Repeat for all of the dough, placing 12 cookies on a baking sheet at a time.

Cook for 8-10 minutes.

When done, allow to cool on the pan for 2 minutes before transferring to a cooling rack before serving.