Mix the eggs and sugar until pale, followed by the olive oil and vanilla extract.
Slowly incorporate the flour. Do not overmix the batter, otherwise, it will result in a dense and chewy cake.
Sprinkle the baking powder over the batter, followed by a pinch of salt, and stir until just combined.
Add in half the apples cut into little chunks, and lemon zest, and give the batter a final quick stir.
Pour the batter in a prepared pan. Decorate the top with the remaining apples, thinly sliced, and pop the cake in the oven.
Bake the cake for approximately 30-40 minutes. Allow it to cool then sprinkle with confectioner's sugar.