Wrap two layers of aluminum foil tightly around the bottom and sides of a 10-inch springform pan to fully cover it. Generously butter the inside of the pan. Preheat the oven to 300ºF (150ºC). Using an electric mixer fitted with the paddle attachment, beat the cream cheese and butter together until smooth. Add the eggs one at a time, mixing well after each addition. Stir in the sour cream and mix until fully combined and smooth. Add the sugar, cornstarch, vanilla, and lemon juice, then beat for about 2 minutes until the mixture is silky and well blended. Pour the batter into the prepared springform pan and place it inside a roasting pan large enough to prevent the sides from touching. Carefully pour boiling water into the roasting pan until it reaches halfway up the sides of the springform pan, taking care not to splash water onto the batter. Bake for 2 hours, or until the top is lightly browned. Note: If using a conventional oven, baking time may be longer than in a convection oven. Remove the springform pan from the water bath, take off the foil, and allow the cheesecake to cool completely at room temperature before unlocking and removing the pan’s rim. Cover the cheesecake and refrigerate until thoroughly chilled, ideally overnight, to ensure it sets properly. Serve plain, or topped with fresh berries, whipped cream, or a drizzle of caramel sauce.