Preheat your oven to 325°F (160°C). In a mixing bowl, combine graham cracker crumbs, melted butter, and sugar until well blended. Press this mixture firmly into the bottom of a greased springform pan to form a solid crust. Bake the crust in the preheated oven for 10 minutes until slightly golden and fragrant. Remove from the oven and allow it to cool completely.

In a medium saucepan, add fresh cranberries, orange juice, sugar, and optional zest. Heat over medium, stirring occasionally, for about 10–12 minutes until the cranberries burst and the mixture thickens to a jam-like consistency. Once cooked, transfer the cranberry jam to a bowl and let it cool completely to room temperature.

In a large mixing bowl, beat softened cream cheese with granulated sugar using an electric mixer until smooth and creamy. Add eggs one by one, mixing gently after each addition. Gradually incorporate sour cream and flour until the mixture is silky and well combined. Pour this cheesecake filling over the cooled crust, spreading it evenly.

Dollop the cooled cranberry jam over the cheesecake filling. Use a toothpick or knife to swirl the jam gently into the filling, creating a marbled effect.

Place the springform pan into a larger baking dish and fill the outer dish with hot water until it reaches halfway up the sides of the cheesecake pan. Bake in the preheated oven for 55–65 minutes, or until edges are set while the center remains slightly jiggly. Turn off the oven, leave cheesecake inside for an additional hour to cool down gently.

After the cooling period, remove the cheesecake from the water bath. Cover with plastic wrap and refrigerate for at least 4 hours or overnight.

While the cheesecake is chilling, prepare the white chocolate mousse by melting white chocolate until smooth. In another bowl, whip heavy cream until soft peaks form. Fold the melted white chocolate into the whipped cream gently.

Once the cheesecake is chilled, spread the white chocolate mousse evenly over the top. Garnish with sugared cranberries and whipped cream if desired. Slice and serve.