Preheat your oven to 350°F (180°C). Grease and flour a 9-inch (22 cm) cake pan to prevent the sponge cake from sticking.
In a large bowl, crack the eggs and whisk them together with the granulated sugar until light and fluffy.
Add the grated orange zest, freshly squeezed orange juice, and vanilla sugar. Mix well to combine.
In a separate bowl, combine the flour, baking powder, and salt. Gradually sift this mixture into the egg mixture, gently folding until just combined.
Add the milk and melted butter (or oil), and gently mix until you have a smooth, light batter.
Pour the sponge cake batter into the prepared cake pan and place it in the preheated oven.
Bake for approximately 30-35 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Remove the cake from the oven and let it rest in the pan for 10 minutes. Then, carefully transfer it to a wire rack to cool completely.
Slice and serve. Dust with powdered sugar or garnish with fresh orange slices.
To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us and our partners to process personal data such as browsing behavior or unique IDs on this site and show (non-) personalized ads. Not consenting or withdrawing consent, may adversely affect certain features and functions.
Click below to consent to the above or make granular choices. Your choices will be applied to this site only. You can change your settings at any time, including withdrawing your consent, by using the toggles on the Cookie Policy, or by clicking on the manage consent button at the bottom of the screen.