Whisk the Ingredients: In a mixing bowl, whisk the eggs, sugar, and vanilla sugar using a mixer on high speed until the mixture doubles in volume and turns pale.

Add Ingredients: Add the lemon zest and juice, oil, and water. Blend until smooth.

Incorporate Flour and Baking Powder: Gradually add the sifted flour and baking powder. Mix on low speed until smooth.

Transfer the Batter: Pour the batter into a greased 22 cm (9-inch) round cake pan. Spread it evenly.

Bake: Bake in a preheated oven at 180°C (350°F) for 40 minutes or until golden and a toothpick inserted comes out clean.

Cool Down: Allow the cake to cool, then use a thin knife to separate it from the sides of the pan and remove it from the mold.

Serve: Place the cake on a plate and dust with powdered sugar if desired.

Slice and Enjoy: Cut into pieces and serve!