• FOR THE CRUST: Preheat oven to 350˚F. Pulse the chocolate graham crackers in a food processor until fine crumbs. Empty crumbs into an 8-inch springform pan. Add the sugar and melted butter. Mix together until all the crumbs are wet, then press onto the bottom and 1½ inches up the sides of the pan.
• Bake at 350˚F for 12 minutes. Remove from oven and set aside to cool. LOWER THE OVEN to 280˚F.
• FOR THE STRAWBERRY PUREE: In a medium saucepan, cook the strawberries, sugar, and lemon juice over medium heat, stirring frequently, until it's starting to boil, the strawberries are soft enough to break up with a spatula, and the sugar is dissolved. Transfer the strawberry mixture to a blender and process until smooth.
• Strain the mixture over a wire sieve back into the pot. Continue cooking over medium heat, stirring frequently.
• In a small bowl, combine the cornstarch and COLD water, creating a slurry. Wait until the strawberry puree comes to a boil, then stir in the cornstarch slurry. Let it come to a rolling boil and thicken up, stirring constantly.
• Remove from heat and place the saucepan on a hot pad in the fridge until cool to the touch.
• FOR THE CHEESECAKE FILLING: Using an electric stand mixer with the paddle attachment, beat the cream cheese and sugar together until creamy and smooth. Scrape the bowl.
• Add the sour cream, lemon juice, and vanilla. Mix again until smooth and fully combined, scraping the bowl as needed. Add the egg and mix until well combined.

Assembly

• Prepare cheesecake for baking in a water bath by wrapping the outside of the springform pan with a double layer of heavy duty foil. Spread the cheesecake batter into the chocolate crust. Gently jiggle and tap the pan to even out the top and release any air bubbles.
• Pour the strawberry puree into a squeeze bottle with a tiny tip. Drop small dots an inch or so apart in a spiral pattern over the cheesecake batter, piping larger dots on the outside, and smaller dots as you go in towards the middle. Save the extra strawberry puree for serving.
• Take a toothpick or sharp pointy knife and drag it through the center of each circle in the same spiral pattern. Be careful NOT to lift the toothpick or knife until you have finished the very last circle. (I started with the outside and worked my way to the middle.)
• Place the cheesecake into a slightly larger roasting pan or baking dish and place it in the oven. Carefully pour hot water halfway up the sides of the springform pan.
• BAKE at 280˚F for 55-60 minutes, until the top looks dull/matte and is slightly puffed up. DO NOT OPEN THE OVEN. Turn the oven off and keep the cheesecake in there for 2 hours.
• Remove cheesecake from oven, take the foil off the pan and let it finish cooling in the refrigerator for 2+ hours. Once chilled, cut the cheesecake with a hot, dry knife for crisp, clean slices. Serve with extra strawberry puree.