1 c. butter
1 c. brown sugar
1 egg yolk
1 tsp. vanilla
2 c. all-purpose flour
1/2 tsp. salt
1 (12 oz.) pkg. milk chocolate chips

Heat oven to 350 degrees. Mix butter, sugar, egg yolk and vanilla. Stir in flour and salt until dough is well blended. Spread in a rectangle about 13 x 10 inches on greased baking sheet, leaving about 1 inch all around edge of baking sheet. Bake 20 to 25 minutes or until nicely browned. Crust will be soft. Remove from oven and immediately place milk chocolate chips on top. Let stand until soft; spread evenly over entire surface. Cut in small squares while warm.