Make Candied Cranberries: Heat water and sugar in a saucepan until dissolved. Let cool slightly, add cranberries, cover, and refrigerate overnight. Drain, coat with sugar, and set aside.
Quick Cranberry Jam: Cook cranberries, sugar, and vanilla over medium heat for 12-15 minutes, stirring frequently. Let cool.
Preheat Oven: Preheat oven to 325°F. Grease a 9-inch springform pan.
Make Crust: Combine graham cracker crumbs, sugar, butter, and vanilla. Press into the pan, covering the bottom and halfway up the sides. Spread half the cranberry jam over the crust.
Prepare Cheesecake Filling: Beat cream cheese and sugar until smooth. Add vanilla, sour cream, and eggs one at a time. Mix in cornstarch and heavy cream. Scrape vanilla bean seeds into batter and mix well. Pour over the crust.
Bake Cheesecake: Place springform pan into a larger roasting pan. Add water to the roasting pan until it reaches halfway up the sides of the springform. Bake for 70-75 minutes. Cool for 10 minutes in the oven with the door ajar, then for 20 minutes on the counter. Chill for 1 hour in the refrigerator.
Spread Jam Layer: Spread remaining cranberry jam over the cooled cheesecake. Cover and refrigerate for at least 4 hours.
Make White Chocolate Mousse: Melt white chocolate according to package instructions. Beat cream cheese until smooth, then mix in white chocolate. Fold in whipped topping. Spread mousse over the cheesecake, reserving some for decorating if desired.
Decorate: Top with candied cranberries if using. Refrigerate until ready to serve.