Preheat the oven to 325°F. Place an 8x8-inch pan on the bottom rack of the oven and fill halfway with boiling water.
Spray a 9-inch springform pan with nonstick cooking spray. Wrap the outside of the bottom of the pan with heavy duty aluminum foil, to prevent any leakage. Set aside.
Graham Cracker Crust: In a medium-size mixing bowl toss together graham crumbs with granulated sugar and butter until fully moistened. Press crumb mixture evenly onto the bottom and halfway up the sides of the pan. Place the pan into the freezer while you make the filling.
In a large bowl of a stand mixer fitted with the paddle attachment, whip together cream cheese, granulated sugar and vanilla extract on medium speed for 2-3 minutes or until completely smooth. Add cornstarch, mix well. (Try not to beat too much air into the filling or the cheesecake could crack.)
Add the eggs one at a time, mixing well after each addition. Scrape sides and bottom of bowl as needed. Stir in sour cream by hand.
Pour cheesecake filling evenly into the crust. Place into the oven.
Bake on the middle rack of the oven for 1 hr 10 - 1 hr 20 minutes or until the center is still slightly loose when the pan is gently shaken. It won't be completely set. Turn off the oven, leave the door slightly ajar, and leave the cheesecake in the oven for 1 hour longer to finish baking.
Remove pan to a cooling rack. Allow to cool for 30 minutes then run a knife gently around the top edge. Cool completely to room temperature. Leave the ring in place, wrap and chill for 8 hours preferably 24 hours.
Slice the cheesecake and serve with fresh fruit and whipped cream or any of your favorite toppings.