In a medium saucepan, combine fresh blueberries, granulated sugar, lemon juice, vanilla extract, and cornstarch. Cook over medium heat for 20–23 minutes, stirring occasionally, until the mixture thickens and becomes jam-like. Remove from heat and allow to cool completely before using in the cheesecake.

In a mixing bowl, cream together granulated sugar, lemon zest, softened unsalted butter, and pure vanilla extract until smooth and fluffy. Gradually mix in all-purpose flour and a pinch of salt until crumbly. Transfer the crumble mixture to the refrigerator to chill.

Preheat the oven to 350°F (175°C). In a food processor, pulse Nilla Wafers until finely crushed, then combine with melted butter and a touch of sugar. Press the mixture firmly into the bottom of a 9-inch springform pan. Bake for 10 minutes, until lightly golden and set, then allow to cool slightly before adding the cheesecake filling.

In your stand mixer, blend softened cream cheese and granulated sugar with cornstarch at medium speed until completely smooth. Add in sour cream, lemon zest, and vanilla extract, mixing just until combined. Slowly add eggs, one at a time, on low speed, ensuring that you mix only until incorporated.

Pour half of the cheesecake filling into the cooled crust. Gently spoon half of the blueberry jam over the filling and swirl with a knife. Pour the remaining cheesecake batter on top, followed by the rest of the blueberry jam, and finally sprinkle the chilled crumble topping evenly over everything.

To bake, place the springform pan inside a larger baking dish filled with warm water. Bake for 1 hour and 15 minutes, or until the cheesecake is set around the edges but still slightly jiggly in the center.

Once baking is complete, turn off the oven and crack the door open. Allow the cheesecake to sit in the oven for an additional hour. Afterward, remove it from the water bath and let it cool completely at room temperature before transferring it to the fridge to chill for at least 8 hours.

In a mixing bowl, beat heavy cream and powdered sugar together until stiff peaks form. Use a spatula to decorate the top of your cheesecake with the whipped cream.