Combine the chocolate crumbs and melted butter and mix well. Press the mixture into the bottom of a 9 inch springform pan and place in the refrigerator or freezer while preparing the filling. Whip the heavy cream with an electric mixer until it holds stiff peaks and place it it the refrigerator. If you have an electric stand mixer such as a KitchenAid, use the paddle attachment to beat the cream cheese on low speed for about 2 minutes; scrape down the sides of the bowl and beat the cream cheese on low speed for 2 more minutes or until smooth and creamy. Add the sugar to the cream cheese and beat on a speed setting of 2 for another 2 minutes. Scrape down the sides of the bowl and fold in the Oreo cookie crumbs by hand with a rubber spatula. Gently fold in the whipped cream until well combined. Pour the mixture into the springform pan (into the crust) and smooth the surface until flat and even; then refrigerate.
4 ounces semisweet chocolate (or use chocolate chips)
1/2 taspoon vanilla
1/3 cup heavy cream
In a sauce pan over low heat, melt the chocolate stirring constantly (do not burn) or use a double boiler technique to melt the chocolate. Remove from the heat and cool slightly. Stir in the cream and vanilla until well blended and cool 2 minutes. Refrigerate until ready to serve cheesecake. Heat slowly in microwave and drizzle over cheesecake slices on serving plate.