INGREDIENTS:
1 cup butter (Grandma said 1/2 cup butter and 1/2 cup margarine)
1 cup brown sugar
1 egg yolk
1/2 tsp. vanilla
2 cups flour
7 oz. dark chocolate (Grandma used 
Special Dark Hershey's bars.
Cousin Michael uses Trader Joe's dark chocolate bars)
1/3 to 1/2 cup chopped walnuts

HOW TO:

Cream 1 cup butter with 1 cup brown sugar.
Add 1 egg yolk, 1/2 tsp. vanilla, and 2 cups flour, and mix well with a mixer.
Press into ungreased 13 x 9 inch pan.  (Try not to make the edges higher.)
Bake in a preheated oven at 350 degrees for 15 minutes.
Remove from oven and scatter 7 ounces of dark chocolate.
When the chocolate melts, spread evenly and sprinkle with chopped walnuts.
It cuts well when cooled but not cooled complete.  Perhaps 1 hour or even two..