Combine crumbs, sugar and margarine, press into bottom of
a 9 inch spring foam pan.
Combine cream cheese and sugar mixing at medium speed
on electric blender until well blended. Add eggs one at a time
mixing well. Combine chocolate pieces and vanilla to
mixture. pour over graham cracker crust. Bake at 450 for 10
minutes, reduce oven to 250 continue baking 35 minutes.
Cool before removing.