Preheat oven to 325 degrees F
Place your foil wrapped springform pan with cooled crust into your other larger round cake pan. This is to keep the water bath from seeping into the springform cheesecake pan. Be ready with your deepdish pan or deep oven tray for the water bath. If you're using a deep oven tray place in the preheated oven now.
With your mixer, beat cream cheese and butter until smooth.
Add eggs one at a time until blended.
Add sour cream until smooth
Add sugar, cornstarch & flour mix, vanilla and lemon juice, beat until smooth, about 2 minutes.
Heat a full kettle of water to boiling and have it ready to pour.
Pour the cheesecake batter into your springform pan (inside a larger cake pan) and place in a another deepdish pan so the sides are not touching OR place on your deep oven tray inside the oven.
With the oven door still open carefully pour your hot water into the deepdish pan or deep oven tray. Fill the deepdish or oven tray as high as you can with hot water. Take extra precautions that you don't splash water on top of the cheesecake or burn yourself pouring or touching the heated oven sides or door.
Close the oven door and bake for 2 hours. Do not open the door during this time.
After two hours you can open the oven door and with oven mits jiggle the pan a little. If the jiggle is mostly focused in the center your cheesecake is done. Close the door, turn off the oven, and keep the cheesecake in for another half hour then open the door for another half hour.
Remove the cheesecake (still inside the larger cake pan) and place on a hot pad. Carefully lift the cheesecake/pan from the larger cake pan and place the cheesecake pan on a wire rack to cool for several hours to room temperature. You can also remove the foil wrap to speed cooling whilst not disturbing the cheesecake. Handle each step very carefully. Do not jossell or shift the cheesecake too much.
Once your cheesecake is at room temperature place it in the refrigerator overnight. Still keep the cheesecake in the springform pan. You can tent foil over the top of the cheesecake just to lightly cover without touching the top!! because it will stick.
The next day remove the cheesecake from the refrigerator. You'll see the cheesecake has settled and most likely come away from the sides. If need be take a thin spatula and gently edge around the sides of the pan. Release the springform latch and lift the edge piece up and away. Your cheesecake is still on the pan base.
Now is the really tricky part!! You need to remove the cheesecake off the pan base whilst keeping in tact the cheesecake, cookie crust base and parchment paper (which is not removed at any time) without cracking or damaging the cheesecake. With a thin plastic cutting board gently edge the board under the parchement paper underneath the whole cake. Gently lift up the cheesecake removing it from the pan base. Lower the cheesecake (still on the thin cutting board) onto the edge of the cake platter. Use a large flat spatula to gently slide the cheesecake (from under the parchement paper) off the cutting board onto the cake platter. Phew, you're done! congratualtions!!
Now decorate as you wish with fresh fruit, chocolate genache, creamcheese frosting or whatever your heart desires.