Preheat oven to 350°F.
Cream butter and sugar. Beat in egg. Whisk together flour, baking soda, cream of tartar and salt. Stir flour mixture into creamed butter mixture. Mix until well blended.
Form dough into 1-inch balls (2-teaspoon sized cookie scoop or rounded teaspoon amounts).
Place balls 2-inches apart on nonstick or lightly greased cookie sheets. Press balls down with a fork, making a crisscross pattern on top of each with tines of fork. If desired, sprinkle cookies with cinnamon sugar or colored sugar.
Bake 12 minutes or until lightly browned. Transfer cookies to wire racks; let cool. Store in airtight container.