1.
Preheat the oven to 400 ºF and grease a baking pan with butter.
2.
Beat the eggs and sugar together in a bowl. Add the
olive oil, baking powder and sieved flour. Slowly fold all the ingredients together (don’t beat too hard). Add the grated orange or lemon zest.
3.
Pour the mixture into a mold, drop the oven temperature down to 180 ºC and bake for about 30 minutes in the middle of the oven with heat from above and below. Do not open the oven door while it is cooking.
4.
Take out of the oven and leave to cool. Remove from the mold and place on a cooling rack for it to dry out. Put on a serving tray and dust with powdered sugar (optional).