5.5Tbspunsalted butterplus more for greasing the pan
Make sure the oven rack is on a lower rung oven and preheat to 350°F. Set the eggs, sour cream, and cream cheese aside to come to room temperature.
Coat a 9-inch springform pan with butter generously. Cut two pieces of foil, each at least 11 inches long and lay one on top of the other in an X shape. Place the pan on top of the foil and wrap the edges of the foil around the outside of the pan.
To make the crust, melt the butter and crush the graham crackers. You can crush them by hand in a bag and beating with a meat tenderizer or throw them in a food processor to pulverize it.
Combine the butter and graham cracker crumbs, stirring until the mixture is wet sand. You know you have the right texture then they hold together if you squeeze a clump. If it doesn't, add more melted butter.
Press the crust into the bottom of the springform pan and use the bottom of a glass or measuring cup to flatten it out evenly. Bake for 8-10 minutes, until the crust shows just a touch of brown at the edge. Let cool completely before adding the batter, but the time it takes to mix the batter should be enough to cool.
Mix together the cream cheese, cornstarch, salt, and sugar in a mixer on medium or medium-low until thick. It should look like cream cheese frosting at this point. Tiny lumps are okay, but try to avoid too many. Scrape down the sides to make sure things are combining evenly.
Add sour cream and vanilla to the mixture and beat on low, scraping down the sides again.
Add the egg yolk and mix on low until just combined, then scrape the sides. Repeat with the eggs, one at a time.
Fill a pyrex measuring cup with water and set aside. Place the cooled springform pan onto a jelly roll pan and pour in the batter. Carefully transfer everything back into the oven. When it's in the oven, pour the water into the bottom of the baking sheet. I typically add 1 1/2 cups of water into the size I use, but the amount isn't critical.
Bake for 40-55 minutes, paying close attention after about 35 minutes. It's done when the top is set and the edges are slightly pulling away from the sides, but the center still has a bit of a jiggle to it. If it starts to brown or crack definitely start to cool it right away.
Turn the oven off and prop the oven door open an inch or two. Let the cheesecake cool for an hour in the cooling oven.
After an hour, remove from the oven and set the springform pan on a cooling rack. Run a knife along the edge of the pan to loosen the sides and let cool until room temperature, roughly another hour. At that point, transfer to the fridge and store uncovered and in the pan for at least 3 hours or until ready to serve.
30 minutes before you're ready to serve, remove from the fridge. When it's time, remove the springform sides and top with whatever topping makes you happy!