In a medium bowl, combine flour, cream of tartar, soda and salt; set aside. In a large bowl, combine butter, sugar and vanilla. Add eggs; mix thoroughly. Gradually, blend in flour mixture. Mix until thoroughly combined. Refrigerate dough for 30 minutes or until chilled.
Preheat oven to 350 degrees. Line 2 large cookie sheets with parchment paper. Combine the remaining sugar and cinnamon in small bowl. Using an ice cream scoop, mold dough into large balls. Roll in cinnamon sugar mixture. Place 4-6 balls on each cookie sheet. Bake 18-20 minutes. Remove immediately from pans. Cool. Makes 11 giant cookies.