Freezer Butter Cookies

Step 1
Blend flour, salt, baking soda, and cream of tartar in a medium bowl. Combine butter, shortening, and sugar in a large bowl; beat with an electric mixer until smooth. Mix in egg and vanilla. Slowly add flour mixture to the sugar blend.

Step 2
Divide dough in 1/2 and form into two 2-inch diameter logs. Shake the candy sprinkles evenly over a sheet of waxed paper. Roll the dough logs over the sprinkles, making sure the sprinkles adhere to the sides. Wrap the logs in waxed paper and refrigerate for 3 hours.

Step 3
Preheat the oven to 350 degrees F (175 degrees C). Line a cookie sheet with parchment paper.

Step 4
Remove 1 dough log from the refrigerator. Unwrap and place on a flat surface. Slice dough into 1/2-inch rounds and place on prepared cookie sheets. Rewrap and return any unused dough to the refrigerator; only slice it just as you are ready to place it on a cookie sheet.

Step 5
Bake in the preheated oven until the bottoms start to brown, 10 to 12 minutes. Cool on the cookie sheets for 1 minute before removing to a wire rack to cool completely. Repeat with remaining dough.