Combine the cranberries, sugar, orange juice, and orange zest in a medium saucepan. Cook over medium heat, stirring occasionally, for about 15 minutes until the berries burst and the mixture turns into a thick sauce.

Press the sauce through a fine mesh sieve to remove the skins and seeds. If you prefer a chunkier sauce, you can leave the skins in, but a smooth sauce works best here.

Use the back of a spoon to press firmly on the solids so you extract as much sauce as possible.

Transfer the strained sauce to a bowl and refrigerate for 1 hour, or until fully cooled.

Preheat the oven to 325°F.

In a bowl, stir together the graham cracker crumbs, sugar, and melted butter until evenly moistened. Press the mixture firmly into the bottom of an 8 or 9 inch springform pan.

Bake the crust for 15 minutes so it holds together better when sliced. If you prefer not to bake it, place the pan in the freezer while you prepare the cheesecake filling.

If baked, let the crust cool completely on a wire rack before adding the filling.

Pour 2 tablespoons of cold water into a small bowl. Sprinkle the gelatin over the water and whisk briefly to combine.

Let the gelatin sit for 5 minutes to soften and bloom.

Add 2 tablespoons of hot water to the gelatin and stir until it dissolves completely. Set aside.

Beat the softened cream cheese with an electric mixer for about 3 minutes, until light, fluffy, and creamy.

Scrape down the sides of the bowl and the beaters so the cream cheese whips evenly.

Add the sweetened condensed milk, lemon juice, and dissolved gelatin to the bowl. If the gelatin has firmed up, microwave it in 5 second bursts to melt it again.

Mix everything together until the filling is smooth and completely incorporated.

Pour half of the cheesecake filling over the cooled crust and spread it evenly.

Spoon about 1/3 cup of the cooled cranberry sauce over the filling, then use a knife to gently swirl it through.

Pour the remaining cheesecake filling over the top and smooth the surface.

Spoon another 1/2 cup of cranberry sauce over the filling and swirl it with a knife for a marbled look.

Tap the pan gently against the counter to settle the filling and release any air bubbles.

Refrigerate the cheesecake for at least 6 hours, or overnight, until completely set.

Run a thin knife around the edge of the pan, release the springform latch, and carefully remove the collar.

Beat the cold heavy cream on medium high speed until soft peaks form. Add the powdered sugar and continue beating for about 2 minutes total, until stiff peaks hold.

Spoon the whipped cream into a piping bag fitted with a star tip.

Pipe the whipped cream over the top of the cheesecake and garnish with sugared cranberries or rosemary sprigs if desired.