Using a hand mixer or stand mixer, beat the powdered sugar, butter, egg, and vanilla until creamy and smooth.
Combine the flour, baking soda, and cream of tartar.
Gradually add the dry ingredients to the wet ingredients until well combined.
Cover the dough very well and refrigerate for 1-2 hours.
Preheat the oven to 350 degrees. Line a baking sheet with parchment paper.
Roll the dough to ½ inch thick on a lightly floured surface.
Cut cookies into whatever shapes you desire.
Make sure everyone gets a turn!
Place them on a baking sheet and bake for 7-8 minutes or until the edges are light golden brown.
Cool cookies on the baking sheet for a minute before transferring them to a wire cooling rack. Allow the cookies to completely cool before frosting them.
Once the cookies are frosted, let your little ones decorate to their heart's content. I let mine decorate with anything I had in the baking cupboard.