01 - Preheat the oven to 325°F. Line the bottom of an 8-inch round cake pan with parchment paper, leaving the sides ungreased to help the cake climb properly.
02 - In a medium bowl, whisk together the flour, sugar, baking powder, and salt until thoroughly blended.
03 - In a large bowl, whisk the egg yolks, Greek yogurt, vegetable oil, vanilla extract, and lemon zest until smooth and fully incorporated.
04 - Add the dry ingredients to the wet mixture and stir gently just until combined. Avoid overmixing to maintain a tender crumb.
05 - Using a clean bowl and electric mixer, beat the egg whites until stiff peaks form. This creates the signature airy texture.
06 - Gently fold one-third of the beaten egg whites into the batter to lighten the mixture. Carefully fold in the remaining whites, preserving as much air as possible for maximum fluffiness.
07 - Transfer the batter to the prepared cake pan and smooth the top surface evenly with a spatula.
08 - Bake for 35 to 40 minutes, or until the top turns golden brown and a toothpick inserted into the center comes out clean.
09 - Allow the cake to rest in the pan for 10 minutes. Run a thin knife around the edges, then invert onto a wire rack to cool completely.
10 - Dust generously with powdered sugar just before serving. Pair with fresh berries or a dollop of whipped cream if desired.