In large bowl, cream butter, shortening and sugars Beat in egg and vanilla. Combine flour, baking soda and salt; stir into butter mixture, mixing well. Stir in chocolate chips and nuts. Drop by teaspoonfuls, 2" apart, onto greased baking sheets. Bake in 350'F. oven 8-10 minutes, just until edges are golden (centers will still be soft). Remove to wire racks to cool.