Remove the skin from the potatoes, cut them into thin slices and put them in a large bowl. In a small pan, melt the butter and drizzle over the potatoes.
Beat the eggs and mix them with the potatoes. Chop the onions, parsley and dill and add to the potatoes.
Season everything with salt and pepper.
Spread half of the potatoes evenly in a well-buttered baking dish. Cover with the defrosted frozen spinach, plucked apart (fresh spinach leaves must be blanched briefly beforehand). Crumble the feta over the top and cover with the remaining potato slices.
Cover with aluminum foil and bake in the oven heated to 180 °C on the middle shelf for 30 minutes.
Tip: Did you know that one bowl of spinach provides almost all the manganese and fiber you need?