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. *don't overmix.
Add eggs one at a time until blended.
Add sour cream until smooth
Add sugar, cornstarch & flour mix, vanilla, and lemon juice, and mix until smooth, about 2 minutes. Avoid overmixing.
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 & slowly pour your hot water into the deep dish pan/oven tray. Fill the tray as high as you can (without reaching the cake pan side top) with hot water. Take extra precautions not to 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. (If not bake for an additional 5-10 minutes until you see this. **Watch closely and be careful not to overbake!!) 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 it on a hot pad. After the larger pan cools a bit carefully lift the inner cheesecake/pan from the larger cake pan and place the main cheesecake pan on a wire rack to cool for several hours to room temperature. You can also remove the foil wrap (only) to speed cooling whilst not disturbing the cheesecake. Handle each step very carefully and try not to allow your fingers to dent or crush the cheesecake top during removal. Do not jostle or shift the cheesecake too much.
Once your cheesecake is 100% cooled and at room temperature place it in the refrigerator overnight. **Your cheesecake is still in the 10" 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 released slightly from the sides. If need be take a thin spatula and gently & slowly edge around the sides of the pan. Release the springform latch and lift the edge piece up and away. Avoid scraping the side of the cheesecake. 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 the cheesecake in tact, cookie crust base, and parchment paper or foil (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 parchment 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 parchment paper) off the cutting board onto the cake platter. Phew, you're done! congratulations!!
Now decorate as you wish with fresh fruit, chocolate genache, creamcheese frosting or whatever your heart desires.
Always hand wash your cake pans as the dishwasher can ruin bakeware.