Cream butter and ¾ cup granulated sugar. Add egg and stir to combine. Add the flour, cream of tartar, baking soda and salt. Mix until completely combined.
Refrigerate cookie dough for 10 minutes. Shape into 18 balls. Dip each ball in flavored sugar of your choice.
Place on a parchment lined sheet pan (cookie sheet with raised edges) and gently flatten before baking. Bake for 11-13 minutes. Let cool and serve. Store in air tight container for up to 3 days or freeze for up to 1 month.
Notes
To make your won cinnamon sugar, add 1 tablespoon cinnamon to ¼ cup of sugar. Mix well.