Preheat the oven to 325°F. Coat an 8x8-inch baking dish or springform pan with non-stick spray, or line with parchment paper.
Separate egg whites from egg yolks. Beat whites in a mixing bowl on medium high speed, until they reach stiff peaks, about 2 minutes. If using a stand mixer, remove beaten egg whites into another bowl and set aside.
Then add egg yolks with the sugar into the mixing bowl and mix until light in color, scraping the bowl. About 2 minutes.
Add melted (and slightly cooled) butter and beat together for a minute or so.
Sift flour into mixture, and blend at medium speed, scraping the bowl.
Add lemon juice, lemon extract and zest, and mix together.
Gradually add warmed milk, and blend together, scraping the bowl. The batter will be very thin.
Add the fluffy egg whites, a third at a time, and gently fold them in with a spatula.
Pour batter into the prepared baking dish and bake for approximately 50 minutes, or until top is a light golden color, and cake is firm to the touch. Check in 5 to 10 minutes before, to ensure it doesn’t overbake.
Allow the cake to cool before slicing and serving. Dust with powdered sugar and top with additional lemon zest (optional).
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.
As with all baked goods, bake times are just estimates. Oven times will vary. It can depend on many factors like if you used a metal or ceramic baking dish or a gas or electric oven or what rack you baked it on. It may take longer in your oven (or shorter) so always make sure you check the cake. You know your oven best.