French Onion Croque Monsieur or Madame
Slowly caramelized sweet onions deliver flavor to these sandwiches covered with melted Gruyère.
- 4 tablespoons butter, divided
- 2 large sweet onions, sliced
- 1 bay leaf
- 1/2 teaspoon ground thyme
- Salt and pepper
- A splash of dry sherry or brandy
- 4 thick slices (about 3/4-1 inch) good-quality, freshly baked white bread
- 2 tablespoons flour
- 1 cup milk
- Freshly grated nutmeg
- 1 rounded tablespoon Dijon mustard
- 8-10 ounces Gruyère cheese, grated
- 4 large eggs (optional)
In a skillet over medium heat, melt 2 tablespoons butter. Add the onions, bay leaf, thyme, salt and pepper and cook until caramel in color and very soft, 25-30 minutes. Deglaze the pan with sherry or brandy.
When the onions are super soft and sweet – but a few minutes shy of perfection – begin your bechamel and pre-heat oven to 375°F. Organize the bread slices on a small baking sheet. Melt the remaining 2 tablespoons butter over medium heat in small pan. Whisk in the flour, cook for 1 minute, then whisk in the milk. Thicken enough to coat the back of a spoon. Season with salt, pepper and nutmeg and remove from the heat. Stir in the Dijon.
Spread the sauce evenly over the bread slices and cover with the onions and cheese. Bake for 8-10 minutes, until golden and bubbly. Serve as-is or top with an egg cooked up, over-easy to over-hard. Serve with a simple green salad and vinaigrette or a small offering of your favorite fruit alongside.