Preheat the oven to 350 F.
In a bowl, whisk together the flour, baking powder, baking soda and salt.
In a bowl of an electric mixer, fitted with a whisk attachment, add the eggs and the sugar.
Whisk again, until the mix turns a light yellow.
Drizzle in the olive oil.
Add the vanilla, orange juice and zest.
Turn to medium speed and mix until combined.
Replace the whisk attachment with a paddle.
Add half of the flour and beat until just combined.
Pour into a prepared 9-inch cake pan.
Bake for 30-35 minutes, until a toothpick inserted into the centre comes out clean.
Set on a baking rack. Let the cake cool slightly.
Unmold the cake and place on a cake plate.
Decorate with fresh orange slices.