Combine shortening, sugar, salt and vanilla. Cream well. Beat in egg yolk. Mix in flour. Spread in thin layer in large pan that has been greased. Not more than 1/4 inch thick. Bake @ 350 for 15-20 minutes. Sprinkle with choc. chips immediately after removing from oven. Spread as they melt. Sprinkle with nuts and cut while still warm.