Peel, wash and quarter the potatoes. Cook in boiling salted water for about 20 minutes. In the meantime put spinach and about 200 ml water in a saucepan. Bring to the boil briefly, cover and cook over medium heat for about 18 minutes.
Stir several times. Drain potato water. Add milk and butter and mash to puree. Season with salt and nutmeg. Put the mashed potatoes and spinach into ovenproof dishes. Beat the eggs on top and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas mark 3) for about 5 minutes.
Season with salt and pepper.