Place your oven racks towards the bottom 1/3 of the oven and preheat to 350 degrees while spraying your 6 inch springform pan with nonstick cooking spray.
Start with your Blueberry Sauce:
Whisk the cornstarch, water and lemon juice until the cornstarch is dissolved in small bowl.
Place blueberries and sugar in pan over medium heat. Stir for 3 minutes, until the blueberry juices release. Add the cornstarch mixture and continue to stir for another 3 minutes, smashing some of the blueberries. The mixture will continue to thicken. Remove from heat and put the mixture through a fine mesh sieve into a bowl. Separate the blueberries from the juice in two bowls. You will need both later.
Mix the graham cracker crumbs, melted butter and sugar in a bowl. Press into the bottom of the prepared pan and slightly on the sides. Wrap the pan in aluminum foil tightly around bottom and sides, so water from the water bath wont enter pan. Bake for 7 minutes and then let cool.
FILLING: Using a stand mixer or hand held, mix the cream cheese and sugar until blended, add the sour cream, vanilla and lemon juice and zest, adding eggs at the end. Do not over mix once you add the eggs. Pour into prepared crust. Add some of the blueberry sauce on top and using a knife, swirl into a pattern. You should have some remaining sauce which you can use at the end with the blueberries. Place cheesecake into a baking pan with sides with 1 inch of warm water inside. Bake approximately 45 - 50 minutes.
Cheesecake will still have a jiggle on top when done. Turn off oven. Open the oven and leave inside for 1 hour. Transfer to refrigerator and let chill overnight or several hours. Add blueberries and sauce on top and whipping cream if you choose.
Tip: Do not overbake or cracking will occur. Should you decide to change this into a 9" spring form pan, you can double the ingredients and change the eggs to 3 large.