When ready to bake, preheat oven to 400 degrees. Mix: softened butter, sugar, and egg. Sift together: sifted flour, cream of tartar, baking soda, and salt. Mix and set aside: 2 Tbsp sugar, and 2 Tsp cinnamon.

Chill the dough for 1 hour in the refrigerator. Roll the dough into balls about the size of walnuts. Roll the balls in cinnamon and sugar mixture. Place the balls about 3 inches apart on ungreased cookie sheets.

Bake until center is almost set and cookie appears lightly browned, 6 to 8 minutes. Cookies will puff up at first, then flatten out with a crinkled top.