With a hand mixer or in a stand mix using the paddle attachment, cream the cream cheese for 1 minute on low speed. Then add the granulated sugar. Once all the granulated sugar is added, scrape down the sides of the bowl and let it mix for 1 minute on low speed.
800 g cream cheese, full fat, 250 g granulated sugar
In a small bowl, mix together the sour cream and cornstarch until smooth. Add it to the cream cheese with the vanilla extract and let it mix on low speed until combined.
200 g sour cream 14-18%, 1 ½ tablespoon cornstarch, 2 ½ teaspoon vanilla extract
Then add two eggs at a time and let it mix on low speed until combined. Once all the eggs have mixed in, scrape down the sides of the bowl and give it a final mix to make sure all the ingredients have incorporated.
4 large eggs
Pour half the cheesecake batter into the spring pan and even it out. Sprinkle the cinnamon sugar over the cheesecake batter in an even layer. Then gently pour over the other half of the cheesecake batter and even it out. Finally add the crumble.
Boil up water in a kettle. Place the springform pan in a 25 cm/10 inch cake pan. Place the cake pan in another baking pan or roasting pan and fill it with hot water. This method will prevent water from getting into the crust.
Alternatively, add a triple layer of aluminium foil around the cake pan to safely seal it from the water before placing it in a water bath. There might be a possibility of water leaking in, so make sure it's covered well if choosing this method.
Bake for 1 hour and 15-20 minutes.
Once the time has passed, give the tray a very gentle shake. The cheesecake should still be a small wobbly in the middle. Turn off the oven and have the oven door slightly open and let the cheesecake cool down in the oven for 1 hour.
Then take it out of the oven and remove it from the water bath. Take off the aluminium foil, if added, and place the cheesecake on a cooling rack. Let it cool down for about 1 hour.
Finally, place it in the fridge and let it set for at least 6 hours, preferable overnight before eating.