Preheat your oven to 180°C (350°F) and line a 9-inch springform pan with parchment paper.
Pulse graham crackers in a food processor until they become fine crumbs.
If you don’t have a food processor, place the crackers in a Ziplock bag and crush them with a cup.
In a bowl, mix graham cracker crumbs, granulated sugar, and melted butter until the crumbs are evenly coated.
Press the mixture firmly and evenly into the prepared pan.
Bake for 7-8 minutes, keeping an eye on it to prevent burning, and let it cool to room temperature.
Reduce the oven temperature to 140°C (280°F).
In a large bowl, beat room-temperature cream cheese, granulated sugar, and vanilla bean extract with an electric mixer until smooth.
Add sour cream, eggs, and egg yolks, mixing until well combined.
Sift cornstarch into the mixture and stir until smooth and lump-free.
Pour the batter over the cooled crust, tapping the pan gently to release air bubbles.
Bake for about an hour, or until the edges are set but the center is slightly jiggly.
Open the oven door halfway and let the cheesecake cool to room temperature for 1-2 hours.
Wrap the cooled cheesecake tightly with plastic wrap and refrigerate for at least 5 hours.
Before serving, sprinkle granulated or caster sugar on top and caramelize with a torch, moving it in a circular motion.