Prepare the Graham Cracker Crust: Preheat your oven to 325°F (165°C). In a medium bowl, mix together the graham cracker crumbs, melted butter, and sugar until the crumbs are evenly coated. Firmly press the mixture into the base of a 9-inch springform pan. Bake for 8-10 minutes, then remove from the oven and let it cool.

Make the Cheesecake Filling: In a large mixing bowl, beat the softened cream cheese until smooth and creamy. Add the sugar and flour, beating until well combined. Incorporate the eggs one by one, mixing gently after each addition. Next, fold in the sour cream, vanilla extract, and lemon juice until well combined. Pour the cheesecake filling over the cooled crust and spread it evenly. Bake at 325°F (165°C) for 60-70 minutes, or until the center is mostly set but still has a slight wobble. Once done, turn off the oven, leave the door slightly ajar, and let the cheesecake cool for an hour. Then, refrigerate for at least 4 hours or overnight to fully set.

Prepare the Blueberry Mousse: In a small saucepan, combine the blueberries, sugar, cornstarch, and lemon juice. Simmer over medium heat for 5-7 minutes, stirring occasionally, until the blueberries soften and the mixture thickens to your desired consistency. Let it cool to room temperature. In a small bowl, sprinkle the gelatin over 2 tablespoons of water and let it sit for a few minutes to bloom. Heat gently until melted, then stir into the cooled blueberry mixture. Fold the whipped cream into the blueberry mixture until fully combined and fluffy.

Assemble the Cheesecake : Spread the blueberry mousse over the chilled cheesecake layer. Smooth the top with a spatula. Refrigerate the assembled cheesecake for at least 2 hours to allow the mousse layer to set fully.

Serve: Carefully remove the cheesecake from the springform pan. Slice and enjoy this heavenly layered dessert!