Cream butter; gradually add sugar, beating well at medium speed of an electric mixer. Add egg and vanilla; beat well. Combine flour, soda, and salt; add to creamed mixture, beating well. Stir in pecans. Shape dough into two 12-inch rolls; wrap in wax paper, and chill at least 2 hours. Unwrap rolls, and cut into 1/4-inch slices; place on ungreased cookie sheets. Bake at 350 degrees for 10 to 12 minutes. Cool slightly on cookie sheets; remove to wire NOTE: Dough may be frozen up to 3 months. Slice dough while frozen, and bake as directed. ----