First peel the potatoes, wash them, cut them into thin slices about 2 mm (with a mandolin or a sharp knife) and leave them to rest in a bowl, well covered with cold water, for at least 30 minutes, so that they lose a little starch and are more crunchy.
In the meantime, prepare the cream: cut the feta into thin slices and then into pieces, then mash it with a fork and mix it with the yogurt, egg and chopped chives.
At this point, start composing the rustic cake: drain the potatoes and dry them with a clean cloth.
Line the mold with parchment paper, then create a base with the potato slices, slightly overlapping them, so as to create a uniform surface, and salt slightly.
Sprinkle the filling over the potatoes, leveling to create a homogeneous layer, then cover with another layer of potatoes.
Season with salt and oil, then cook for 30 minutes in a preheated convection oven at 200 ° C.
The Greek potato pie is ready: decorate with rosemary, then let it cool before serving.