Marbled Pumpkin Cheesecake with a Brownie Crust

Preheat the oven to 325°. Lightly butter a 9-inch springform pan. In a medium saucepan, melt the butter with the chopped chocolate over low heat, stirring constantly. Remove the melted chocolate mixture from the heat and let it cool slightly, then stir in the sugar and the lightly beaten egg until blended.

In a small bowl, whisk the flour with the baking powder and salt. Add the dry ingredients to the melted chocolate mixture. Stir the chopped walnuts into the brownie batter. Spread the batter in the prepared springform pan and smooth the surface with a spatula. Bake for 10 minutes, or until risen and dry to the touch. Let cool completely. Wrap the outside of the pan in a large sheet of foil. Leave the oven on.

In a medium glass bowl, melt the chopped chocolate in a microwave oven on high for about 1 minute, stirring halfway through. In a large bowl, using an electric mixer, beat the cream cheese until smooth. Add the sugar and beat until light and fluffy. Add the eggs, 1 at a time, beating well between additions. Beat in the cornstarch and vanilla. Add 1 cup of the cheesecake batter to the melted chocolate and stir until well blended. Beat the pumpkin puree and the cinnamon, nutmeg and cloves into the remaining cheesecake batter.

将四分之三的南瓜芝士蛋糕面糊倒在布朗尼硬皮上。将巧克力面糊倒在南瓜芝士蛋糕面糊的顶部。如果巧克力面糊太厚而无法倒入，请在高高的微波炉中加热10秒钟。将剩余的南瓜芝士蛋糕面糊倒入巧克力面糊顶部。使用桌刀做一些装饰性漩涡：不要超女。

将弹簧盘放在中等的烤盘中。在烤盘中加入足够的热水，以达到弹簧盘侧面的一半。在烤箱中央的热水浴中烘烤南瓜芝士蛋糕1 1/2小时，或直到边缘牢固，但在中心略微摇晃。关闭烤箱，支撑几英寸的门，让芝士蛋糕在温暖烤箱中的水浴中站立1小时，或者直到完全固定为止。

Remove the marbled pumpkin cheesecake from the water bath and refrigerate it until thoroughly chilled, at least 4 hours or overnight. Remove the foil and springform pan ring from the cheesecake. Carefully transfer the cheesecake to a platter, cut into wedges and serve.