- Preheat the oven to 350°F (175°C) and grease a small cake pan. 
- Mix wet ingredients – In a bowl, whisk the egg, salt, and sugar until slightly frothy. Stir in the grated lemon zest (or vanilla sugar), oil, yogurt, and lemon juice until well combined. 
- Add dry ingredients – Sift in the flour and baking powder, and gently mix until you have a smooth batter. Do not overmix. 
- Bake – Pour the batter into the prepared cake pan and bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. 
- Cool & Serve – Let the cake cool before removing from the pan. Serve plain, dusted with powdered sugar, or topped with fruit and enjoy!