In a jug mix together the olive oil and milk then set aside. Sift the flour, baking powder and salt together in another bowl, then set aside. In another large bowl whisk the eggs, sugar and zests together until thick and fluffy- this will only take a minute or so with electric beaters. Add in the dry ingredients and olive oil mix then fold everything together gently and pour into the greased tin.
Bake for 35 minutes, then leave to cool for 5 minutes before removing the tin and transferring to a wire rack to cool completely.
Frosting
To make the frosting mix together the olive oil and icing sugar then lightly spread over the top and sides of the cooled cake. Decorate with olive leaves if desired.