1/2 c. butter
1/2 c. other shortening
1 c. brown sugar
2 c. flour
1 egg yolk
1 tsp. vanilla
6 oz. pkg. chocolate chips
1/2 c. nuts

Blend first 3 ingredients until creamy; add flour, yolk, and vanilla. Spread on lightly buttered cookie sheet and bake 20 minutes at 350 degrees. Shut off oven. Sprinkle chips and leave in oven 5 minutes to soften them. Spread over cookie sheet pastry; top with nuts and cut into 2 inch squares.