Preheat oven to 375 degrees F. Lightly grease baking sheets.

Cream butter, shortening, white sugar and confectioners' sugar together until light and fluffy. Beat in the egg and the vanilla.

Sift the flour, baking soda, salt and cream of tartar together. Add the flour mixture to the sugar mixture and blend.

Use cookie scoop to place cookie balls on a greased baking sheet.

Bake at 375 degrees F for 10 to 12 minutes or until lightly browned.