1/2 cup butter
1/2 cup shortening
1/2 cup brown sugar
1 cup white sugar
1 egg
2 cup flour
2 tsp. baking soda
1 tsp. cream of tartar
1/2 tsp. salt
1 tsp. vanilla
2 cup chocolate chips

Cream together butter, shortening and brown and white sugar. Add the egg and beat. Sift and add flour, soda, cream of tartar, and salt. Add 1 tsp. vanilla and the chocolate chips. Drop by spoonfuls onto cookie sheet.

Bake at 350°F for 10-12 minutes. The secret is not to bake them too long.