Preheat the oven to 350 degrees if not still preheated from the crust.
In a large bowl of a stand mixer, mix the cream cheese, corn starch, brown sugar and granulated white sugar together with a paddle attachment on medium speed for two minutes until everything is smooth and there are no lumps. (You can alternatively use a hand mixer). Scrape down the bottom and sides of the bowl to ensure everything has been mixed well.
32 oz (907 g) cream cheese, softened at room temperature, ¾ cup (165 g) brown sugar, packed, ½ cup (100 g) granulated white sugar, 2 tablespoon (16 g) cornstarch
Add the melted brown butter, vanilla, and sour cream to the cream cheese mixture and mix for 1 minute on medium speed. Scrape the sides and bottom of bowl again to ensure everything is mixed together.
brown butter from above, ⅓ cup (82 g) sour cream, at room temperature, 2 teaspoon vanilla
At this point, stop and put a pot of water on the stove to start boiling for the water bath. You will want enough water to go up about 1 ½ inches on the sides of the springform pan.
Next add in the eggs and egg yolks one at a time to the cheesecake batter. Mix on medium speed, ensuring that each is fully mixed in before adding the next. As soon as the last one is fully mixed in, turn off the mixer. Do not over mix the batter.
3 eggs, at room temperature, 2 egg yolks, at room temperature
Pour the batter into the prepared springform pan with the crust. Place the cheesecake in a large roasting pan in the oven. Slowly pour the hot water into the pan around the cheesecake being careful not to splash the cheesecake.
Bake the cheesecake for 1 hour. When an hour is up, turn off the oven and crack the door open. It helps to use a wooden utensil to keep the oven door slightly open. Let the cheesecake stay in the oven for 1 more hour. The cheesecake will continue to bake as it is cooling. (This is the best method I’ve used when making cheesecake and it results in a perfectly baked top with no cracks or sinking every time.)
Once the 2 hours are up, remove the cheesecake from the oven and go around the edges of the pan with a butter knife to loosen the crust from the sides of the pan. Let the cheesecake cool completely on a wire rack. Cover with tin foil or plastic wrap, and refrigerate until cold, at least 8 hours.(I bake it the night before and let it refrigerate overnight).