Combine crumbs and margarine; press onto the bottom of a 9-inch springform pan. Bake at 350 degrees F for 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 for 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.
Source: E-Cookbooks.net