Melt-In-Your-Mouth Sugar Cookies
["1c. butter or margarine, softened", "1 c. vegetable oil", "1 c. sugar", "1 c. sifted powdered sugar", "2 eggs", "1 tsp. vanilla extract", "4 1/2 c. all-purpose flour", "1 tsp. baking soda", "1 tsp. salt", "1 tsp. cream of tartar"]
["Combine butter, oil and sugars in a large mixing bowl; beat well at medium speed of an electric mixer.", "Add eggs, one at a time, beating after each addition.", "Stir in vanilla.", "Combine flour, soda, salt and cream of tartar in a medium mixing bowl; add to creamed mixture, beating well.", "Shape dough into 1-inch balls. Place on an ungreased cookie sheet.", "Flatten with bottom of a glass dipped in sugar.", "Bake at 350\u00b0 for 8 to 10 minutes.", "Cool on wire racks.", "Yields 8 dozen."]
["butter", "vegetable oil", "sugar", "powdered sugar", "eggs", "vanilla extract", "flour", "baking soda", "salt", "cream of tartar"]