Banana Nut Cheesecake

Combine crumbs and margarine; press onto the bottom of a 9-inch springform pan. Bake at 350 degrees F., 10 minutes. Combine cream cheese, sugar and banana, mixing at medium speed on electric mixer until well blended. Add eggs, one at a time, mixing well after each addition. Stir in walnuts, pour over crust. Bake at 350 degrees F., 40 minutes. Loosen cake from rim;cool before removing rim pf pan. Melt chocolate pieces and margarine with water over low heat, stirring until smooth. Drizzle over cheesecake. Chill.