A recipe from Nigella Lawson, the ultimate kitchen goddess. Ingredients: Cheesecake base: 1 1/3 cups graham cracker crumbs 1/2 stick butter 1 tablespoon cocoa Cheesecake filling: 6 ounces bittersweet or semisweet chocolate, chopped small 2 1/2 cups cream cheese 3/4 cup superfine sugar 1 tablespoon custard powder 3 large eggs 3 large egg yolks 2/3