Wash the spinach (fresh Swiss chard can also be used, for example) and drain well, then sort, remove coarse stalks. Put the spinach in a saucepan and cover over medium
Let the heat collapse, then chop.
Peel and finely dice the onions and the clove of garlic, then sauté in the butter until translucent.
Stir in the spinach and 50g creme fraiche and season to taste with salt, pepper and nutmeg.
Grate the cheese.
Mix the rest of the creme fraiche with the eggs and cheese and season with salt and pepper.
Preheat the oven to 210 degrees (hot air to 190 degrees).
Wash, peel and cut the potatoes into fine slices (preferably with a slicer).
Layer the slices in the prepared pan like a roof tile and season with salt. Spread the spinach over it and brush with the cheese cream.
Bake the casserole on the middle rack for about 50-60 minutes, until the surface is golden brown.