Preheat oven to 325°F. Line a small cake pan with parchment paper.
In a bowl, whisk together Greek yogurt, egg yolks, protein powder, cornstarch, sweetener, vanilla, and baking powder until smooth.
In a separate bowl, beat egg whites with a pinch of salt until stiff peaks form.
Gently fold egg whites into the batter a little at a time so it stays fluffy and airy.
Pour into the pan and bake 35–45 minutes until golden on top and slightly jiggly in the center.
Let cool slowly before slicing for that perfect cloud texture.
