Recipe Courtesy Lynda Haynes from “The Ace Bakery Cookbook”.
Preheat the oven to 375°F (190°C).
In manageable batches, plunge the spinach into boiling water. Allow the water to come to a boil again. Cook for 1 minute and drain on paper towels. Roughly chop.
Melt the butter in a frying pan large enough to hold all the ingredients except the eggs. Add the onions and sauté over medium heat for 2 minutes. Stir in the garlic, then mix in the spinach and cook for 1 minute. Sprinkle with the flour and stirring, gently cook for 1 minute more. Pour in the warm milk and bring to a simmer. Cook, stirring, until the mixture thickens, about 5 minutes. Add the nutmeg, salt, and pepper. The recipe can be prepared to this point up to 1 day ahead.
Spoon the spinach mixture into an 8- to 10-cup (2- to 2.4-L) buttered baking dish (or 4 to 8 individual baking dishes). Make 8 indentations in the spinach and break an egg into each well. Sprinkle each egg with a pinch of salt. Bake for 15 to 18 minutes or until the egg white is set but still soft.
Mix together the breadcrumbs, melted butter, and the Parmigiano Reggiano. Remove the baking dish from the oven. Turn on the broiler. Sprinkle the crumb mixture over the eggs and place under the broiler for 30 seconds, until lightly golden. Serves 4 to 8, depending on appetites.