Preheat the oven to 325 degrees Fahrenheit. Toast the pecan pieces on a baking sheet in the preheated oven for 6-8 minutes. Remove from the oven and allow to cool to room temperature. Lower the oven temperature ot 300 degrees Fahrenheit. In a food processor fitted with a metal blade, chop the cookies and the pecans until they are in crumbs about 20-30 seconds. Set aside until needed.
Coat the bottom of a 9-by 3-inch springform pan with 1 tsp melted butter. Use your hands to press l cup of crumbs to a uniform and level thickness on the buttered bottom of the pan. Set aside.
To prepare the chocolate cheesecake, heat l inch of water in the bottom half of a double boiler over medium-high heat. Place the semi-sweet chocolate and coffee in the top half of the double boiler.
Tightly cover the top with film wrap and allow to heat for 6 to 8 minutes.
Remove from the heat and stir until smooth.
Place 3/4 pound softened cream cheese, 3/4 cup sugar, and 1/2 tsp salt in the bowl of an electric mixer fitted with a paddle. Beat on low for l minute and on medium for 2 minutes. Scrape down the sides of the bowl, then beat on medium for 2 more minutes and on high for 2 minutes. Scrape down the bowl. Add 3 eggs , one at a time, beating on high for 20 seconds and scraping down the bowl after each addition. Then beat the mixture for 1 minute more on high. Add l teaspoon vanilla extract and beat on medium for l5 seconds. Add the melted chocolate mixture, then beat on medium for 30 seconds. Remove the bowl from the mixer. Use a rubber spatula to finish mixing the batter until it is smooth and thoroughly combined. Pour the cheese cake mixture into the prepared springform pan, spreading evenly.
Keep at room temperature while preparing the pumpkin cheesecake batter.
To prepare the pumpkin cheesecake, coat the inside of a 9-by 1 1/2 inch cake pan with l tsp butter. Line the pan with an 8 inch square of parchment paper. Coat the parchment paper with the remaining tsp butter.
Set aside until needed.
Place l pound softened cream cheese, 3/4 cup sugar, the flour, and 1/2 tsp salt in the bowl of an electric mixer fitted with a paddle . Beat on low for l minute and on medium for 2 minutes. Scrape down the sides of the bowl, then beat on medium for 2 more minutes and on high for 3 minutes.
Scrape down the bowl. Add 3 eggs one at a time, beating on high for 20 seconds and scraping down the bowl after each addition. Add l tsp vanilla extract and beat on medium for l5 seconds, then beat for 2 more minutes on high. Add the pumpkin puree, cinnamon, allspice and cloves, then beat on medium for 30 seconds. Remove the bowl for the mixer. Use a rubber spatula to finish mixing the batter until it is smooth and thoroughly combined.Pour the pumpkin cheesecake mixture into the prepared cake pan, spreading evenly.
Place a 9 by 1 1/2 inch cake pan partially filled with 4 cups of hot water on the bottom rack of the 300 degree oven (the bottom rack should be at least 3 inches below the center rack). Place both cheesecakes on the center rack of the oven and bake for l hour and l0 minutes, until the internal temperature of the cheesecake fillings reaches l70 degrees. Turn off the oven and allow the cheesecakes to remain in the oven for an additional 20 minutes. Remove from the oven and cool at room temperature for 20 minutes. Refrigerate the chocolate cheescake for l hour, but keep the pumpkin cheesecake at room temperature (do not remove either cake from the pan).
Pour l cup of Semisweet Chocolate Ganache over the top of the chilled chocolate cheesecake. Spread the ganache evenly over the top of the cake.
Invert the pumpkin cheesecake onto the layer of ganache. Gently press down on the cake to set in place. Wrap the entire springform pan with film wrap and refrigerate for 3 hours to set.
The cheesecake can now be released from the spring form pan. Remove the film wrap and wrap a damp, hot towel around the sides of the pan (the towel should be large enough to completely wrap around and cover the sides of the pan) and hold around the pan for abo*ut l min. Carefully relase and remove the springform pan. Using a cake spatula, smooth the sides of the cake with 2 to 3 tablespoons ganache. Spread the remaining amount of ganache evenly across the top of the cake. Press the remaining cookie/pecan crumbs into the sides of the cake, coating evenly. Refrigerate for at least 30 minute before cutting and serving.
Heat the blade of the serrated slicer under hot water before cutting, and run it under hot water after making each slice. Place a piece of cheesecake in the center of each plate and serve. *Separate