Toffee Bars
["1 c. butter or margarine", "1 c. packed brown sugar", "1 egg yolk", "1 tsp. vanilla", "2 c. flour", "1 (12 oz.) pkg. semi-sweet chocolate chips", "1 c. chopped walnuts"]
["Beat butter for 30 seconds. Add brown sugar and beat until fluffy. Beat in egg yolk and vanilla. Gradually add flour and beat well. Press evenly in 13 x 9 x 2 baking pan and bake for 20 minutes in 350\u00b0 oven. Immediately sprinkle chocolate pieces on top and let stand until softened (about 5 minutes) and spread evenly. Sprinkle with nuts. Cut into bars while warm."]
["butter", "brown sugar", "egg yolk", "vanilla", "flour", "semi-sweet chocolate chips", "walnuts"]