Wash the spinach and boil in a large quantity of water for 25 to 30 minutes. Drain and squeeze to remove the excess water, then chop on a bread board.

Brown the onion in 100 grams of butter. Add the salt, pepper and the chopped spinach. Cook 2 minutes more, then pour into a round, high-sided cake mold. Spread it evenly, then make 8 hollow places with the back of a spoon. Break an egg into each hollow. Prepare a cream sauce with 50 grams of butter, 50 grams of flour, the milk and a little salt. Add the grated cheese and stir. Pour this sauce over the eggs, sprinkle with bread crumbs and melted butter and place in the oven until the eggs are cooked. Serve.