Mix the flour with the baking powder.
Separate the eggs into whites and yolks.
Cut the peaches into slices and put them in a bowl.
Sprinkle the vanilla sugar over them.
Preheat the oven to 180 degrees Celsius.
Start by adding the egg yolks and the sugar in a large bowl. Mix well.
Add the milk, oil, vanilla essence, and lemon zest, and mix.
Add the flour and mix again, to incorporate it into the dough.
Separately, whisk the egg whites until stiff.
Fold the whisked egg whites into the dough. Be careful not to over-mix.
Pour the batter dough into a baking tray lined with baking paper.
Arrange the peaches on the top and sprinkle with the brown sugar.
Bake for 35-40 minutes, depending on the depth of your tray.
Let the cake cool down inside the tray, before cutting it.