Creamy, rich sauce, salty prosciutto and runny fried eggs—the perfect breakfast sandwich.
- 4 tablespoons butter
- 3 tablespoons flour
- 2 cups whole milk
- ¼ teaspoon salt
- ⅛ teaspoon pepper
- ⅛ teaspoon nutmeg
- 1 cup grated Gruyère cheese
- ¼ cup grated Parmesan cheese, plus more for garnish
- 8 thick-cut slices of French bread
- 4 teaspoons Dijon mustard
- 4 eggs
- 16 slices of prosciutto
- 1 tablespoon finely diced chives
- Heat a saucepan over medium and melt 3 tablespoons of butter. When the butter has melted, add the flour and stir together. Cook, while continuing to stir, for 1 minute. Add milk and continue stirring until your roux has incorporated and the milk thickens, about 5 minutes. Remove from the heat.
- Add your salt, pepper, nutmeg and cheese, and stir to combine. Stir the sauce every minute or so, until the cheese has melted.
- Preheat your broiler.
- Lay 4 pieces of bread on a baking sheet. Spread 1 teaspoon of Dijon on each piece. Top with 2 pieces of prosciutto and 1 tablespoon of sauce. Cover with a second piece of bread and coat the top with 2-3 tablespoons more sauce.
- Cook under a broiler until the sauce is melted, golden and bubbling, 2- 3 minutes. Turn off the broiler and transfer sandwiches to the lower rack of the oven to keep warm.
- While the sandwiches are cooking, heat a remaining tablespoon of butter in a pan over medium. Crack eggs and fry until the whites are set but the yolks are runny.
- Top the sandwiches with an egg and 2 pieces of prosciutto. Grate some Parmesan cheese and sprinkle on chives.