Brown sugar, packed
Preheat oven to 350~F. In large bowl, with electric mixer, cream butter well; blend in brown sugar, egg yolk and vanilla. By hand mix in flour, 1 1/2 bags Heath Bits and nuts. Press into ungreased 15 1/2 x 10 1/2in. jelly roll pan. Bake 18 to 20 minutes, or until browned. Remove from oven and immeadiately sprinkle remaining 1/2 bag Heath Bits over top. Cool slightly; cut into bars while warm.