For crust, lightly butter sides of a 10-in. (25-cm) springform pan. In a food processor, whirl cookies until crumbs form. They should measure about 3 cups (750 mL). Add melted butter and whirl until evenly mixed. Press onto bottom of pan. Wrap bottom and outer side of pan with heavy-duty foil. Refrigerate while preparing filling.
Preheat oven to 325F (160C). Put a kettle full of water on to boil. For filling, cut cheese into cubes, then place in a large bowl. Using an electric mixer, beat until smooth. Then gradually beat in sugar, flour, spices and vanilla. Beat in eggs, one at a time, then pumpkin and candied ginger, scraping down sides of bowl with a spatula between additions. Remove crust from refrigerator. Pour in filling and smooth top. Place wrapped springform pan in a broiler pan or shallow-sided roasting pan and place in oven. Pour enough boiling water into broiler pan to come about 1-in. (2.5-cm) up side of springform pan.
Bake in centre of preheated oven until filling is almost set when springform pan is jiggled, about 1 hour. Remove broiler pan from oven. Set on a wire rack. Let cake stand in water in pan just until water cools, about 40 min, then remove cake from water. Remove foil from pan. Run a knife around inside edge of pan to help prevent cracking. Cool, then cover and refrigerate until well chilled, at least 4 hours, preferably overnight. If making ahead, wrap in plastic, then overwrap with foil and freeze up to 1 month.
For topping, chop chocolate and place in a small bowl. Add butter. Microwave on medium, stirring once, until almost melted, about 2 min. Remove and stir until smooth. Drizzle over cold cheesecake, then refrigerate cake until firm, about 10 min. Slice into wedges and serve. Or place wedges on plates and drizzle chocolate sauce overtop.
Nutrition (per serving)
Flavoured with cinnamon, ginger, cardamom and allspice, this silky cheesecake is a decadent alternative to traditional pumpkin pie.