A splendid citrus-scented, vanilla and chocolate marbled cheesecake, with a cocoa-infused graham cracker crust.

Black and White Cheesecake

1 1/2 cups graham cracker crumbs
1/4 cup granulated sugar
3 tablespoons cocoa powder
1/2 cup butter, melted
3 (8-ounce) packages cream cheese
1 cup plus 2 tablespoons granulated sugar
2 tablespoons all-purpose flour
1 teaspoon grated lemon peel
1 teaspoon grated orange peel
3 large eggs
2 large egg yolks
1/2 teaspoon vanilla extract
1 (6-ounce) package or 1 cup semi-sweet chocolate, melted
3 tablespoons whipping cream

1. Preheat oven to 325°F (160°C).
2. Combine graham cracker crumbs, sugar, cocoa powder and butter in a small bowl; combine thoroughly. Press firmly into a 10-inch springform pan and set aside.
3. In medium bowl, with an electric mixer at medium speed, beat the cream cheese with sugar until light and fluffy. Beat in flour and the citrus peels. Slowly beat in eggs, egg yolks and vanilla.
4. In a separate bowl, combine the melted chocolate with cream. Pour two-thirds of the cheesecake filling over the crust. Fold the chocolate mixture into the remaining filling until thoroughly combined. Using a knife, swirl the chocolate filling into the plain filling to get a marbled effect. Bake 40 minutes.
5. Turn off the oven, open the door and let the cake stand for 20 more minutes inside the oven. Cool on a rack. Refrigerate overnight.

Makes 12 servings.