Preheat oven to 350 F. Lightly grease your 9” round cake pan with butter (you can also use an 8x8” brownie pan if thats what you have). I used a springform pan.
Separate your eggs into two bowls, one with the whites and one with the yolks. The bowl with the whites should be large.
Using an electric hand mixer, beat each for 30 seconds. Add the beaten yolks, vanilla, yogurt, butter and zests to the egg whites. Beat until creamy. Next add the powered sugar and mix until just incorporated. Lastly, add the flour and baking soda and mix until no flour is visible. Transfer batter to your pan and spread out evenly with a rubber spatula.
Bake for 30-35 minutes or until toothpick comes out clean. Remove from oven and allow to cool for 10 minutes prior to removing from pan. Allow to cool completely if decorating with whip cream and berries. You can also just top with some powdered sugar to serve. I also topped mine with some lemon zest as a final garnish.
Notes
Traditionally, we serve this cake with some powdered sugar on top and some lemon zest for aesthetic. The whip cream and fruit was done for Mother's Day.