Preheat overn to 350 degrees.

In the bowl of an electric mixer cream the butter well. Blend in brown sugar, egg yolk and vanilla. Slowly add in the flour, and mix until just combined. Fold in the 1 cup of Toffee Chips and pecans if using. Press dough into an ungreased 15x10 inch jelly-roll pan.

Bake for 18-20 minutes, or until golden brown. Remove from oven, and immediately sprinkle with the crushed Heath Bars. Cool for 10 minutes - slice into bars. You can remove from pan to cool, or leave in the pan. But you want to cute while still warm, or they are very hard to cut through.