Step 1

In a large bowl, cream butter, shortening and brown sugar until light and fluffy, 5-7 minutes. Beat in egg and vanilla. Combine flour, baking soda, cream of tartar and salt; gradually add to creamed mixture and mix well. Stir in toffee bits and pecans. Shape into a 10-in. roll; wrap in plastic. Refrigerate until firm, 4 hours.

Step 2

Preheat oven to 375°. Unwrap dough and cut into 1/2-in. slices. Place 2 in. apart on baking sheets coated with cooking spray. Bake until lightly browned, 9-11 minutes. Cool 1-2 minutes; remove from pans to wire racks to cool completely.