Bet the butter until it is soft.  Beat in about half the flour.  Add the sugar, egg, vanilla, baking soda and cream of tartar and beat until thoroughly combined.  Beat in the remaining flour.  Cover and chill in the refrigerator for about an hour.  Preheat oven to 375 degrees.  Combine the sugar and cinnamon in a shallow bowl.  Shape the dough into 1-inch balls.  Roll the balls in the sugar mixture to coat.  Place the balls 2 inches apart onto an ungreased cookie sheet.  Bake until the edges are slightly browned (about 10 minutes).

Our comments:  Hattie made these as a school project and was the hit of her class.  We are hoping that Hattie keeps supplying us with awesome recipes.