Begin by carefully separating the egg yolks from the whites using a clean bowl for each. Set the egg whites aside for later.

Using an electric mixer, beat the egg whites on high speed until stiff peaks form, about 3-5 minutes.

In the same bowl that held the yolks, add the monkfruit sweetener and vanilla extract if using. Beat until light and fluffy, about 4 minutes.

Add the non-fat Greek yogurt to the creamed yolk mixture and stir until fully incorporated.

Sift the cornstarch into the mixture and fold it in until fully combined.

Carefully fold the whipped egg whites into the yogurt mixture using a spatula.

Line a 7x11-inch baking dish with parchment paper for easy removal after baking.

Place the lined baking dish inside a larger roasting tray. Pour boiling water into the outer tray until 1/4 to 1/3 full.

Preheat your oven to 330°F (160°C) and bake the cake for 45 minutes. Then increase the temperature to 350°F (180°C) and bake for another 15 minutes.

Once baked, turn off the oven, crack the door ajar, and let the cake cool in the oven for 1-2 hours.