Step 1: In a medium bowl, combine 1 ½ cups graham cracker crumbs, ¼ cup granulated sugar, and 6 tablespoons melted unsalted butter.
Step 2: Press the mixture firmly and evenly into the bottom of a 9-inch springform pan. Use the flat bottom of a glass or your knuckles to get a compact crust.
Step 3: Bake the crust at 350°F (175°C) for 8-10 minutes, then let it cool while you prepare the filling.
Step 4: In a separate bowl, whisk together 1 cup all-purpose flour, ½ cup granulated sugar, and ½ teaspoon ground cinnamon.
Step 5: Cut 6 tablespoons cold unsalted butter into small cubes and add to the flour mixture. Use a pastry blender or your fingertips to cut the butter into the dry ingredients until coarse crumbs form.
Step 6: Gently fold in 1 cup fresh blueberries. Set aside in the refrigerator.
Step 7: In a large bowl, using an electric mixer, beat four 8-ounce packages of softened cream cheese on medium speed until smooth and creamy.
Step 8: Gradually beat in 1 ½ cups granulated sugar until well combined, scraping down the sides of the bowl as needed.
Step 9: Add 1 teaspoon vanilla extract, the zest of 1 large lemon, and 2 tablespoons fresh lemon juice. Mix until just combined.
Step 10: Beat in 4 large eggs, one at a time, mixing on low speed until each egg is just incorporated. Be careful not to overmix after adding the eggs, as this can introduce too much air, leading to cracks in your cheesecake.
Step 11: Pour the cheesecake filling over the cooled graham cracker crust.
Step 12: Sprinkle the chilled lemon blueberry crumble topping evenly over the cheesecake filling.
Step 13: Place the roasting pan with the springform pan into the preheated oven. Carefully pour hot water into the roasting pan until it comes about halfway up the sides of the springform pan.
Step 14: Bake at 325°F (160°C) for 60-70 minutes, or until the edges are set but the center still jiggles slightly when gently shaken.
Step 15: Turn off the oven, crack the door open, and let the Lemon Blueberry Crumble Cheesecake cool in the water bath for 1 hour. This slow cooling process helps prevent cracking.
Step 16: Remove the cheesecake from the water bath and the roasting pan. Carefully remove the foil. Let it cool completely on a wire rack at room temperature.
Step 17: Once completely cool, refrigerate for at least 6 hours, or preferably overnight, before serving. Chilling is essential for the cheesecake to fully set and develop its rich flavor.