Triple-Chocolate Cheesecake

From Martha Stewart

An American-born beauty, the cheesecake gets upgraded with a triple dose of chocolate. It's in the crust, in the filling, and over the top. To help prevent cracks, turn off the oven and let the cheesecake sit inside for an hour. To cut the cleanest slices, use a knife dipped in warm water.
Serves 12

Ingredients
    1 package (9 ounces) chocolate wafer cookies
    6 tablespoons unsalted butter, melted
    4 bars (8 ounces each) cream cheese, room temperature
    1 1/2 cups sugar
    1/2 teaspoon salt
    4 large eggs
    1 cup sour cream
    8 ounces semisweet chocolate, melted
    Chocolate Ganache, for topping

Method
Preheat oven to 325°F. Assemble a 9-inch springform pan with the raised side of the bottom facing down.
   
In a food processor, pulse cookies until finely ground. Add butter, and pulse to moisten. Transfer to prepared pan, and press crumbs firmly and evenly into the bottom. Place pan on a rimmed baking sheet; bake 10 minutes, and set aside.
   
Wipe out bowl and blade of food processor. Add cream cheese, sugar, and salt; blend until smooth. With motor running, add eggs, then sour cream, and finally chocolate; blend filling until smooth, scraping down sides of bowl as needed.
   
Pour filling onto crust, and bake just until set, 1 hour. Turn oven off, and let cheesecake sit 1 hour in oven, without opening (this helps prevent cracking).
   
Run a thin knife around the edge of the pan (this helps prevent cracking, too); leave in pan, and cool completely on wire rack. Cover loosely and refrigerate, at least 6 hours or up to overnight.
   
Prepare Chocolate Ganache. Unmold cheesecake. Spread ganache in center of cheesecake; let set before serving.