1. Prepare the chocolate crumb crust. Preheat the oven to 350°F.2. Beat the cream cheese and sugar in a large bowl until creamy. Gradually add the eggs, heavy cream, vanilla, and salt, and beat until smooth; set aside.3. Reserve 2 tablespoons of chocolate chips. Pour the rest of the chocolate chips into a large microwave-safe bowl. Heat in the microwave on medium power for 1 minute and 30 seconds; stir. If necessary, return to the microwave in 15-second increments, stirring after each heating, until the chocolate is melted.4. Gradually add 1 1/2 cups of the cream cheese mixture to the melted chocolate. Spread 2 cups of the chocolate mixture over the crust.5. Add 2 more cups of the plain cream cheese mixture to the chocolate mixture; pour 2 cups of this mixture over the first layer in the springform pan. Add the cream cheese mixture to the remaining chocolate mixture, stir, and pour over the second layer.6. Bake for 50 to 55 minutes or until the center is almost set. Remove from the oven and place on a wire rack. Immediately run a knife between the pan and the edge of the cake. Let cool to room temperature.7. Pour the remaining chocolate chips and shortening into a large microwave-safe bowl. Heat on medium power for 30 seconds; stir. If necessary, return to the microwave in 10-second increments, stirring after each heating, until the chocolate is melted. Drizzle over the top of the cake. Cover and refrigerate for several hours until the cake is cold. Cover and refrigerate any leftover cake.Chocolate crumb crust: Mix 1 1/2 cups of vanilla wafers (about 45 cookies), 1/2 cup of powdered sugar, and 1/4 cup of cocoa; stir in 1/4 cup (1/2 stick) of melted margarine or butter. Press the mixture into the bottom of a 9-inch springform pan and up the side to a height of 1 1/2 inches.