Chocolate Crumb Crust:
1 1/3 cups chocolate wafer crumbs
1 tablespoon granulated sugar
4 tablespoons unsalted butter at room (temperature)
1 1/2 cups semisweet chocolate pieces
2 tablespoons butter
1/4 cup Kahlua
1 pound cream cheese, softened and cut into small pieces
2 large eggs
1/3 cup granulated sugar
1/4 teaspoon salt
1 cup dairy sour cream
1 cup semisweet chocolate pieces
1/3 cup Kahlua
1/3 cup light corn syrup
Chocolate Crumb Crust: Combine wafer crumbs, sugar and butter, mixing well. Put mixture in an even layer over bottom of a 9-inch springform pan.
Filling: Heat oven to 325 degrees F.
Slowly heat chocolate, butter and Kahlua in a small saucepan, stirring until chocolate melts and mixture is smooth. Set aside and cool slightly.
Add softened cream cheese, continuing to beat until smooth. Beat in eggs, then beat in sugar, salt and sour cream. Gradually beat in chocolate mixture. Pour into chocolate crumb crust. Bake for 40 minutes, or just until filling is barely set in center.
Remove from oven and let stand at room temperature at least 1 hour.
Before serving, if desired, spread on a thin layer of sour cream or cr me fraiche and drizzle mocha sauce over top of cake. Cut in small slices with a thin sharp knife dipped in cold water. Refrigerate leftovers.
Mocha Sauce: Combine ingredients in a saucepan over low heat. Stir constantly until chocolate melts and mixture is smooth. Serve warm or at room temperature.