Preheat oven to 425°F. Line a 9-inch springform pan with enough parchment to hang 2 inches over the sides of the pan. Set aside.
To make the cheesecake batter, start by placing the cream cheese, sugar, and mascarpone cheese into the bowl of a stand mixer fitted with the paddle attachment. Beat together on high speed for 2 minutes. Scrape the sides of the bowl down intermittently to ensure everything is well incorporated.
32 ounces cream cheese, 1⅓ cups granulated sugar, 8 ounces mascarpone cheese
Add the eggs and beat together for 30 seconds.
3 large eggs, 3 egg yolks
Add the heavy cream, sour cream, vanilla, and lemon juice and mix until incorporated.
1⅓ cups heavy cream, ½ cup sour cream, 2 teaspoons pure vanilla extract, 1 teaspoon lemon juice
Lastly, add the cornstarch and flour and mix just until combined.
3½ tablespoons cornstarch, 2 tablespoons all-purpose flour
Pour the cheesecake batter into the parchment-lined pan and smooth out.
Place the pan into the oven to bake for 45 minutes.
Once baked, turn the broiler on and broil for 30 seconds or until the top is dark brown but not black. Remove from the oven and place onto a cooling rack to cool completely.
Once cooled, cover and place in the fridge to chill for at least 8 hours. Once chilled, release the springform and unmold to serve.