Preheat oven to 350F and spray an 8-inch springform pan with non-stick vegetable spray.
Crust: In bowl, combine crumbs, water and margarine; mix well. Pat onto bottom and sides of springform pan. Refrigerate.
In food processor, combine ricotta and cottage cheeses, sugar, egg and vanilla; process until smooth. Add cocoa and flour; process just until combined. Pour into pan and bake for 30 minutes or until set around edge but still slightly loose in centre.
Topping: Meanwhile, stir together sour cream, sugar and vanilla; pour over cheesecake. Bake for 10 more minutes. (Topping will be loose.).
Let cool and refrigerate for at least 3 hours or until set.