Preheat the Oven: Preheat your oven to 180°C (350°F). Grease and line an 8-inch round cake pan with parchment paper to prevent sticking.

Prepare the Cake Batter: Separate the Eggs: Separate the egg yolks from the egg whites. Place the egg whites in a large, clean bowl.

Beat Egg Whites: Using an electric mixer, beat the egg whites until soft peaks form. Gradually add half of the granulated sugar and continue beating until stiff peaks form. The mixture should be glossy and hold its shape.

Mix Egg Yolks and Sugar: In another bowl, whisk together the egg yolks and the remaining granulated sugar until the mixture is pale and slightly thickened.

Add Milk and Oil: Mix the milk and oil into the egg yolk mixture. If using vanilla extract, add it at this stage.

Incorporate Dry Ingredients: Sift the cake flour into the egg yolk mixture and gently fold until combined. Be careful not to overmix to avoid a dense cake.

Fold in Egg Whites: Gently fold the beaten egg whites into the egg yolk mixture in thirds. Use a spatula to fold, lifting the mixture from the bottom and turning it over. This process helps to maintain the airiness of the batter.

Bake the Cake: Pour the batter into the prepared cake pan and smooth the top with a spatula. Bake in the preheated oven for 25-30 minutes, or until the cake is golden brown and a toothpick inserted into the center comes out clean.

Cool and Serve: Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely before frosting or serving.