Preheat oven to 350°F.

In a food processor, process graham cracker sheets into fine crumbs.

Press evenly into the bottom of a 9" springform pan.

Bake for 10 minutes, then remove to a wire rack to cool.

Reduce the oven temperature to 325°F.

In a small bowl, whisk cornstarch and water together; set aside.

Combine raspberries, ¼ cup granulated sugar, and 1 tablespoon blood orange juice in a medium saucepan.

Cook for 5 minutes over medium heat, crushing the berries with a fork as they cook down.

Stir cornstarch slurry into the raspberry mixture and bring to a boil.

Cook for another minute until sauce thickens, continuing to crush any raspberry pieces.

Strain sauce through a fine mesh sieve into a medium bowl to remove seeds, pressing the berries with the back of a spoon, pushing all of the liquid out.

Discard seeds and set sauce aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat cream cheese until smooth and creamy.

Combine 1¼ cups granulated sugar and blood orange zest in the bowl of your food processor and pulse a few times to infuse the sugar with the citrus oils.

The sugar will turn light orange and look slightly wet.

Dump the citrus sugar into the cream cheese and beat on medium-high speed for 3 minutes, until the mixture is light and fluffy, scraping down the sides and bottom of the bowl.

Add eggs one at a time, beating until just incorporated, then scraping down the sides and bottom of the bowl between each addition.

Add 4 tablespoons blood orange juice and the vanilla extract and mix until just combined. Remove the bowl from the stand mixer and stir in heavy cream and sour cream by hand with your rubber spatula.

Place your springform pan inside a large roasting pan.

Pour cheesecake filling into your springform pan and jiggle slightly to even out the top.

Drizzle the raspberry sauce over the top.

With a butter knife, drag it over the raspberry sauce in a zig zag pattern, up and down and left to right, to create a marbled effect on the surface of the cheesecake.

Don't put the knife in all the way to the bottom or you'll dig up your graham cracker crust.

Place the springform pan (encased in a cake pan or foil) into a large roasting pan and place on the middle rack of your oven.

Carefully pour boiling water into the roasting pan until the water comes about halfway up the sides of the springform pan.

Bake for 90 minutes, until the edges are set, but the center jiggles a bit.

Turn off the heat, prop the oven door open with the handle of a wooden spoon, and let the cheesecake rest in the oven for 1 hour.

Carefully remove the springform pan from the water bath and set it on a wire rack to cool to room temperature.

Cover and refrigerate until chilled, 4 hours or overnight.

When ready to serve, carefully run a small offset spatula around the edge of the cheesecake to loosen the sides.

Unlatch the springform ring and remove it.

Place fresh raspberries and slices of blood oranges on the top for garnish.

Serve with raspberry coulis sauce.