Peel and finely chop the onion. Heat 1 tablespoon of oil in a saucepan. Fry the onion in it. Add frozen spinach and 5-6 tbsp. water. Cover and steam over medium heat for about 15 minutes, stirring occasionally.
For the béchamel sauce, heat butter in a pot. Dust with flour and briefly sauté lightly. While stirring, deglaze with 300 ml water and milk. Bring to the boil and simmer for about 5 minutes. Season to taste with salt and pepper.
Heat 2 tablespoons of oil in a large frying pan. Fry the eggs, possibly in 2 portions, for about 5 minutes until they are fried, turning them once. Salt them. Season spinach with salt, pepper and nutmeg and drain well.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer).
Spread some sauce on the bottom of a high, square casserole dish (approx. 2 1/2 l capacity). Place about 3 lasagne plates on top. Approx. 1/3 spinach, half live
Repeat once, putting the fried eggs in between. Finish off with lasagne dishes, spinach and sauce. Rub the gouda directly on top. Bake in a hot oven for about 40 minutes until golden brown.