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. Stir in milk and 400 ml water. Bring to the boil, stir in broth 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 in it, possibly covered in 2 portions, for about 5 minutes until they become fried eggs. Season with salt. Season spinach with salt, pepper and nutmeg and drain well.
Spread a little béchamel on the bottom of a high square casserole dish (approx. 2 1/2 l capacity). Place about 3 lasagne plates on top. Spread about 1/3 spinach, half meatloaf and again sauce on top.
Repeat once, putting the fried eggs in between. Finish off with lasagne dishes, spinach and sauce. Grate the Emmental finely and sprinkle over it. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for approx. 40 minutes until golden brown.
Drink tip: red wine, e.g. a Zweigelt.