Prepare the Pan: Line the bottom of an 8- or 9-inch springform pan with parchment. Wrap outside of the pan with foil (for water bath).
Separate Eggs: Place yolks in one bowl, whites in another. Whip egg whites with a pinch of salt until stiff peaks form. Set aside.
Make the Cloud Batter: In a mixer or large bowl, blend: Cream cheese, Sour cream, Heavy cream, Sweetener, Egg yolks, Vanilla, Lemon juice, Cornstarch or almond flour. Mix until silky smooth with no lumps.
Fold In Egg Whites: Gently fold the fluffy whites into the batter in 3 additions. This step creates the cloud-like texture — be gentle!
Bake in a Water Bath: Pour batter into pan. Place pan inside a larger pan filled with 1–2 inches of hot water. Bake at 320°F (160°C) for 45–55 minutes, then reduce temperature to 300°F (150°C) for another 20 minutes.
Cool Slowly: Turn off oven and leave cake inside with door cracked open 30 minutes. This prevents sinking.
Chill: Refrigerate at least 2–3 hours, preferably overnight, for best texture.
