Preheat the oven to 350°F. Grease a 9-inch springform pan with non-stick cooking spray or butter. Place the pan on a large sheet of heavy-duty aluminum foil (or two sheets of regular aluminum foil), and tightly wrap the sides and the bottom of the springform pan. Set aside.
Prepare the graham cracker crust. In a small bowl, mix the graham cracker crumbs, brown sugar, and salt. Add the melted butter and stir until well combined. Transfer this mixture to the prepared springform pan. Press down using a spoon or the back of a measuring cup. Bake for about 8-10 minutes or until golden brown. Remove from the oven and let cool completely.
Prepare the cheesecake filling. In a large mixing bowl, whisk together cream cheese, ¾ cup sugar, and cornstarch for 2-3 minutes or until creamy. Then, whisk in the egg yolks until well incorporated. Add the sour cream, lemon juice, lemon zest, and vanilla extract. Whisk until combined. Set aside.
In a separate large mixing bowl, using a handheld or stand mixer, Beat the egg whites and salt until frothy. Add the cream of tartar and continue beating until doubled in volume. Gradually add the remaining 1/2 cup of sugar until stiff peaks form.
Using a rubber spatula, carefully fold the whipped egg whites into the cream cheese mixture in a few additions, 1/3 at a time. Do not overmix to deflate the mixture. Mix until just combined. Spoon the cheesecake filling over the cooled graham cracker crust.
Place the springform pan in a roasting pan and carefully pour about 1 inch of hot water into the roasting pan. Transfer to the oven and bake for about 50-60 minutes or until lightly golden brown on top.
Turn off the oven and open the door slightly (about 2 inches). Leave the cheesecake in for an additional hour. Remove from the oven and let cool to room temperature on a cooling rack. Chill in the refrigerator overnight.
Prepare the blueberry topping. Heat 1 cup of blueberries, sugar, lemon juice, and 1/4 cup of water in a small saucepan over medium-high heat. Let simmer for about 5 minutes or until the blueberries start to break down. In a small bowl mix the cornstarch and 2 tbsp of water. Add to the saucepan, stir to combine, and let simmer for a few minutes until the syrup thickens. Remove from the heat and stir in the remaining 1 1/2 cups blueberries.
Remove the chilled cheesecake from the refrigerator. Slice, top with blueberry topping, and serve!