Directions: Preheat oven to 350 degrees. To make crust, combine the Oreo crumbs, sugar and melted butter until well mixed. Using the back of a spoon, press the mixture firmly on the bottom and up the sides of a 9" spring form pan. Set aside. For the cake batter, beat together the softened cream cheese, sugar and vanilla with an electric mixer. Add the eggs and mix to combine. Remove 1 cup of the batter and place in a separate bowl. Stir the melted chocolate into the 1 cup of batter and mix well. To assemble, first pour the chocolate batter into the prepared crust. Top with the plain batter. Bake for 40 minutes or until set. Allow to cool and refrigerate overnight. Cristina recommends that you bake the cake on a baking sheet to avoid bottom spills.