Preheat the oven to 325°F (163°C). Position a rack in the lower-middle section of the oven. Lightly grease the bottom and sides of a 9-inch (23 cm) springform pan. To prevent water from entering during baking, wrap the outside bottom and sides with several layers of heavy-duty aluminum foil. For more reliable protection, place the springform pan inside a slightly larger solid cake pan that fits within the roasting pan. Set a kettle or pot of water to heat for the water bath.

In a medium mixing bowl, combine: 1½ cups (150 g) graham cracker crumbs ¼ cup (50 g) granulated sugar 6 tablespoons (85 g) melted unsalted butter Stir until the crumbs are evenly moistened. The mixture should resemble damp sand and hold together when squeezed between your fingers. If some crumbs remain dry, continue mixing until the butter is evenly distributed.

Transfer the crumb mixture to the prepared springform pan. Press it firmly and evenly across the bottom using the flat base of a measuring cup. Bake for 10 minutes, until the crust looks slightly darker and smells lightly toasted. Remove from the oven and allow it to cool while preparing the filling. Keep the oven at 325°F (163°C).

Place 24 ounces (680 g) softened cream cheese in a large mixing bowl. Beat on medium-low speed for about 2 minutes, until smooth and free of visible lumps. Add 1 cup (200 g) granulated sugar and continue mixing for another 1 to 2 minutes. Scrape down the sides and bottom of the bowl with a rubber spatula. The mixture should look thick, creamy, and smooth rather than fluffy. Avoid whipping excessive air into the filling, which can cause the cheesecake to rise too much and crack as it cools.

Add the following ingredients: 1 cup (240 g) full-fat sour cream ¼ cup (60 ml) fresh lemon juice 2 tablespoons (12 g) fresh lemon zest 1 teaspoon (5 ml) vanilla extract Mix on low speed until evenly combined. The filling should become slightly looser while remaining thick and creamy. Scrape the bowl to ensure the lemon zest and sour cream are evenly distributed.

Sprinkle 2 tablespoons (16 g) all-purpose flour over the filling and mix on low speed until no dry streaks remain. Add the 3 large eggs, one at a time, mixing briefly after each addition. Stop mixing as soon as each egg is incorporated. Use a spatula to fold the batter gently a few times, checking for any unmixed cream cheese along the bottom of the bowl. The finished batter should be smooth, glossy, and thick but pourable.

Pour the cheesecake filling over the cooled graham cracker crust. Smooth the surface gently with an offset spatula or the back of a spoon. Tap the pan lightly on the counter two or three times to release larger trapped air bubbles. Avoid vigorous tapping, which may disturb the crust.

Place the protected springform pan inside a large roasting pan. Transfer the roasting pan to the oven rack, then carefully pour hot water into the roasting pan until it reaches approximately 1 inch (2.5 cm) up the outside of the protected cheesecake pan. Make sure no water enters the cheesecake. The water bath helps the filling cook gradually and reduces the likelihood of dry, overbaked edges.

Bake at 325°F (163°C) for approximately 55 to 65 minutes. The cheesecake is ready when: The outer 2 to 3 inches look set. The surface appears mostly matte rather than wet. The center still has a gentle wobble when the pan is nudged. The center moves as one soft unit rather than rippling like liquid. For an additional doneness check, an instant-read thermometer inserted near the center should register approximately 150–155°F (66–68°C). Avoid waiting until the entire cheesecake is firm. The center continues to set as it cools. The total cook time, including the 10-minute crust bake, is approximately 1 hour 10 minutes.

Turn off the oven: Carefully remove the roasting pan's hot water if it can be done safely without moving the cheesecake, or leave the water bath undisturbed. Crack the oven door open slightly and let the cheesecake cool inside for 1 hour. This gradual temperature change helps reduce surface cracking and sudden shrinking.

Carefully remove the cheesecake from the oven and water bath. Remove the protective foil and place the springform pan on a wire rack. Allow the cheesecake to cool for approximately 1 hour, until it is no longer warm. Refrigerate promptly and do not leave it at room temperature for more than 2 hours total. Do not release the springform ring yet. If the surface has a small crack, it will not affect the flavor and can be covered with the optional garnish.

Once fully chilled, run a thin knife around the inside edge of the springform pan. Carefully release and remove the outer ring. Transfer the cheesecake to a serving plate, leaving it on the pan base if moving it would risk breaking the crust. For cleaner slices, use a sharp knife dipped in hot water and wiped dry between cuts.

If using the optional whipped cream garnish, combine: ½ cup (120 ml) cold heavy whipping cream 1 tablespoon (8 g) powdered sugar Whip until medium-stiff peaks form. Pipe or spoon the whipped cream around the cheesecake's edge. Sprinkle with 1 teaspoon (2 g) finely grated lemon zest, if desired. Slice into 12 portions and serve chilled.