Adjust the oven rack to the lower-middle position and preheat oven to 350°F (177°C). Tightly wrap 1 or 2 sheets of of heavy-duty aluminum foil around the bottom and sides of a 9-inch or 10-inch springform pan and set aside.

Whisk the cornstarch, lemon juice, and warm water together in a small bowl until the cornstarch has dissolved. Set aside. Warm the blueberries and sugar together in a small saucepan over medium heat. Stir continuously for about 3 minutes, until the blueberries begin to release their juices. Add the cornstarch mixture and continue to stir for another 2–3 minutes, smashing some blueberries as you go. The mixture will begin to thicken. Remove from heat and press the mixture through a fine mesh sieve into a small bowl to separate the cooked berries from the thickened juice. Transfer the cooked blueberries to another bowl and set both (the cooked berries and the juice) aside.

If you’re starting out with full graham crackers, use a food processor or blender to grind them into fine crumbs. Pour into a medium bowl and stir in the sugar until combined, and then stir in the melted butter. The mixture will be sandy. Try to smash/break up any large chunks. Pour the mixture into the prepared pan. With medium pressure using your hand, pat the crumbs down into the bottom and partly up the sides to make a compact crust. Tips: You can use a small flat-bottomed measuring cup to help press down the bottom crust and smooth out the surface, but do not pack down with heavy force because that makes the crust too hard. Simply pat down until the mixture is no longer crumbly. For more shaping technique tips, see the graham cracker crust recipe page.

Bake the crust for 10 minutes. Allow to slightly cool as you prepare the filling.

In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the cream cheese and granulated sugar together on medium speed until the mixture is smooth and creamy, about 3 minutes. Add the sour cream and vanilla extract and beat until fully combined. With the mixer running on low speed, add the eggs one at a time, beating after each addition until just incorporated. Stop the mixer as soon as the final egg is incorporated; over-mixing can cause the cheesecake to deflate.

Pour the cheesecake batter into the crust and smooth the top. Drop spoonfuls of the smooth blueberry sauce onto the batter. Using a knife, gently swirl as shown in the photo above. If you have leftover blueberry sauce, mix it with the cooked blueberries you set aside, tightly cover, and refrigerate until you serve the cheesecake.

(If needed for extra visuals, see How to Make a Cheesecake Water Bath; the visual guide and video will assist you in this step.) Boil a kettle/pot of water. You need 1 inch of water in your roasting pan for the water bath, so make sure you boil enough. I use an entire kettle of hot water. Place the wrapped springform pan inside of a large roasting pan. Carefully pour the hot water into the roasting pan and place it in the oven. (Or you can place the roasting pan in the oven first, then pour the hot water in—whichever is easier for you.) Quickly shut the oven door to trap the steam inside.

Bake the cheesecake for 55–65 minutes, or until the center is almost set. If you notice the cheesecake browning too quickly on top, tent it with aluminum foil halfway through baking. When it’s done, the center should still slightly wobble when you gently tap or shake the pan.

Turn the oven off and open the oven door slightly. With the door ajar, let the cheesecake sit in the oven in the water bath as it cools down for 1 hour. After 1 hour, remove the cheesecake from the oven and water bath, discard the foil, and place the springform pan on a wire rack to cool completely at room temperature. After it has cooled, cover and refrigerate the cheesecake for at least 6 hours or up to 2 days.

Run a knife around the edges of the springform pan to help loosen the cheesecake, then remove the outer rim. Using a sharp knife, cut into slices for serving. For neat slices, wipe the knife clean and dip it into warm water between each slice. Top with reserved blueberry sauce and whipped cream, if desired.

Cover and store leftover cheesecake in the refrigerator for up to 4 days.