Preheat your oven to 350 degrees Fahrenheit and place a rack in the center position of the oven. Grease six 6-ounce ramekins to ensure easy removal later. Place them into a 9×13 baking dish with at least 2-inch high sides to create a water bath.
In a large bowl, whisk together the egg yolks, milk, lemon zest, lemon juice, melted butter, and salt. This mixture will be the base of your cake, so mix it well until it’s smooth and creamy.
Next, stir in the flour and granulated sugar until fully combined. The batter should be thick and glossy, with all the dry ingredients incorporated.
In a separate medium bowl, beat the egg whites until medium-soft peaks form. This is where the magic happens; the whipped egg whites will add airiness to your cake.
Gently fold one-third of the beaten egg whites into the lemon batter. Use a rubber spatula and be gentle to avoid deflating them. It’s okay if some white remains.
Once the first third is incorporated, fold in the remaining egg whites until no visible white from the egg whites remains. The batter should look light and fluffy at this stage.
Evenly separate the batter between the prepared ramekins. Use a measuring cup to make this process easier and cleaner. Fill each ramekin about three-quarters full, leaving room for rising.
Place the baking dish with the ramekins on the center rack of the oven. Carefully fill the baking dish with water until it is halfway up the sides of the ramekins. This water bath helps the cakes cook evenly.
Bake for 40 to 45 minutes, until the cakes rise and turn lightly golden on top. Keep an eye on them towards the end to avoid over-baking, which can lead to a dry texture.
Once baked, carefully remove each ramekin from the baking dish, being cautious not to drip water onto the other cakes. Let them cool on a cooling rack for about 15 to 20 minutes.
Before serving, dust with powdered sugar and add fresh berries on the side if desired. Enjoy the delightful creation you've baked!
