Combine graham cracker crumbs and melted butter in a bowl. Stir until well mixed, then press firmly into the bottom of a 9-inch springform pan. Chill in the fridge while you prepare the filling.
In a large bowl, beat softened cream cheese and sugar with an electric mixer until smooth and creamy.
In a separate bowl, whip heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until fully combined and fluffy.
Spread half of the cheesecake mixture evenly over the chilled crust.
Arrange Christmas Tree Cakes in a single layer across the top (press them down slightly into the filling).
Spread the remaining cheesecake mixture on top, smoothing the surface evenly with a spatula.
Cover and refrigerate for at least 6 hours, or overnight, until firm.
Heat the heavy cream in the microwave until just steaming. Pour over the chopped white chocolate and let sit 2 minutes, then stir until smooth. Cool slightly before pouring.
Pour the white chocolate ganache over the chilled cheesecake and smooth the top.
Drizzle with red decorating icing in a zigzag pattern and sprinkle green sanding sugar evenly on top.
Return to the fridge for 30 minutes to set the topping. Slice and serve chilled.