Peel and finely chop the onion and garlic. Heat the butter in a wide saucepan. Fry onion and garlic in it until transparent. Add frozen spinach and about 150 ml water and bring to the boil. Cover and allow to defrost at low heat for about 15 minutes.
Stir from time to time.
Drain the spinach and squeeze it out gently. Season with salt, pepper and nutmeg and place in four small or one large casserole dish. Beat 1 egg on each. In a preheated oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see
manufacturer) for about 10 minutes. Season with salt and pepper. Cheese crostini taste good with it.