Have all ingredients at room temperature. Preheat oven to 350°. Line an 8-inch springform pan with parchment paper and brush melted butter or oil on the bottom and sides of pan.
For Crust: Place graham crackers and orange zest in a food processor and give it 15 to 20 long pulses, until crackers resemble grains of sand. Add melted butter and pulse until butter coats crumbs and mixture looks and feels like wet sand.
Press graham cracker mixture into springform pan bottom, making sure to press firmly. The bottom of a metal measuring cup works well to smooth out base. Bake for 8 minutes. Remove from oven and let cool.
For Cheesecake: Reduce oven temperature to 200°.
Place white chocolate in a microwave-safe bowl. Heat for 30 seconds and stir. Return to microwave and heat for another 30 seconds. The chocolate should be almost completely melted. The remaining small chunks will melt as the chocolate cools. White chocolate can also be melted in a double boiler. Set aside to cool.
Place remaining ingredients in a blender. Pulse 10 to 15 times to mix. Scrape down the sides of blender with a rubber spatula. Pulse or blend quickly until well mixed. Add still-warm white chocolate and pulse a few more times to mix thoroughly. At this point, it is good to let mixture set for 10 minutes to release any air bubbles.
Pour mixture into prepared pan over the graham cracker base. Bake for 2 ½ hours. To tell if cake is ready, gently shake pan. If sides of cake are firm, but the center still has a little bit of wiggle, then it is ready. (I use this method.) If the center is too wiggly, return to oven for 10 minutes. Keep checking in 10-minute intervals. Alternatively, insert an instant read thermometer into the cake center; it’s ready when the temperature is 160°.
Remove cake from oven and let cool for an hour. Refrigerate cheesecake for a minimum of 3 hours. (The secret to perfect slices of cheesecake is to refrigerate cake until it is set firmly.) This cake is best when made at least one day before serving, as the chocolate flavor enhances with time.
For Cranberry Pomegranate Jam: Place cranberries, pomegranate juice, orange juice or water, sugar and orange zest in a heavy-bottomed pan with a lid. Heat mixture over medium heat until it begins to bubble. Stir gently, making sure not to press the cranberries, until sugar dissolves.
Allow mixture to simmer with lid on for approximately 20 minutes. Berries will pop after a few minutes, but it is best not to smash them, as the fruit bits can make syrup grainy. The pectin in the cranberries will cause the syrup to thicken slightly.
Remove from heat and allow to cool for 10 minutes uncovered. Stir in bitters and vanilla, and mix well. Pour into a lidded glass jar and allow to cool to room temperature, then refridgerate until ready to use.
To serve: Remove from springform pan. Then use a knife dipped in hot water to cut smooth slices. You can either top whole cheesecake with jam or spoon jam over individual slices. Garnish with white chocolate curls or shavings, if desired.
Variation: Cheesecake can be made in a 9-inch springform pan. Bake cake for approximately 2 hours and check for the gentle wiggle at that time.