1 1/4 c. graham cracker crumbs
3/4 c. plus 2 tbsp. sugar
2 oz. (1/2 stick) unsalted butter, melted
6 oz. semi-sweet chocolate
1/4 c. rum
1 lb. cream cheese
1/2 c. sour cream
1 tbsp. vanilla extract
5 eggs

Preheat oven to 325 degrees. Butter inside of spring-form pan well and cover the outside (bottom and sides) with a sheet of heavy-duty aluminum foil, shiny side out. This reflects heat away from cheesecake and prevents it from baking too fast and becoming overcooked. Mix graham cracker crumbs with 2 tablespoons of the sugar and add melted butter. press evenly on bottom and sides of pan and refrigerate until ready to use.

Cut chocolate into small pieces. Combine with rum in top of double boiler and place over barely simmering water. (Do not let water touch underside of top pan.) Stir gently until chocolate is melted and smooth and set aside.

In bowl of electric mixer, beat cream cheese until light and fluffy. Gradually beat in sugar, sour cream, and vanilla. Add eggs, one at a time. Mix well and remove bowl from mixer stand. Place bowl over a pan of hot water and mix until smooth (do not let water touch bottom of bowl). Pour about 1 1/4 cups of this batter into a separate bowl and set aside. Whisk remaining batter with the chocolate, then stir over hot water until smooth.

Take spring-form pan from refrigerator and fill with chocolate batter. Gently pour plain batter over top and make swirls down into the chocolate batter with a fork. Place on middle rack of oven and bake for 50 minutes. Cool to room temperature; remove foil and rim of pan and refrigerate overnight. Serves 10 to 12.