This gooey French classic is a timeless favorite for a reason; the creamy béchamel, thinly sliced ham, Gruyère, crisp bread and fried egg pair so well together. This fancy grilled cheese is the kind of sandwich I have dreams about. What is the difference between a Croque Madame and Croque Monsieur? The distinction is that the Croque Monisuer is a grilled ham and cheese with béchamel on top while the Croque Madame is the same but with the addition of a perfectly cooked, sunny side up egg on top. Beschamel is one of the “5 French Mother sauces” where roux is whisked together with milk to make a creamy white sauce. That base can then be used to make any other variation by adding whatever suits you. In this recipe I add cheese and thyme.
For the béchamel:
3 tablespoons unsalted butter
1 tablespoon minced yellow onion
2 tablespoons all-purpose flour
1 sprig fresh thyme
1 cup whole milk
¼ cup grated Gruyère
¼ cup grated Parmesan cheese
Kosher salt, as needed
Ground black pepper, as needed
4 slices of French bread, cut ½” thick
4 ounces thinly sliced ham, about 6 slices
1 cup grated Gruyère
2 tablespoons canola oil
2 large eggs
For the béchamel:
Heat a medium saucepan over medium heat, add the butter and allow to melt. Add the onion and sauté, stirring frequently, until the onions are translucent and tender, about 5 minutes.
Add the flour and stir to combine, let cook about 1 minute, to cook the flour taste off. Add the thyme sprig to the pot then gradually add the milk and bring to a simmer, whisking constantly then reduce the heat to low and continue to cook until the sauce has slightly thickened, about 15 minutes. Slowly add the Parmesan and Gruyère, whisking constantly until completely combined.
Season with salt and pepper to taste and remove the thyme sprig or use a fine mesh strainer to strain the sauce. Return the sauce to a simmer on low heat until ready to use.
Preheat broiler on high. Line a baking sheet with parchment paper.
Place the slices of bread on the baking sheet. Top 2 of the slices of bread with 3 slices of ham each. Top all of the slices with about 3 tablespoons of the béchamel sauce, then use a knife to evenly spread it over the bread. Top each slice of bread with about 3 to 4 tablespoons of the Gruyère cheese.
Broil, checking frequently, until the cheese is melted and bubbling, about 5 minutes.
Heat a medium nonstick skillet over medium heat. Add the canola oil and heat through. Gently break each egg into the pan and fry until the whites of the egg have set and the yolk has thickened but is still runny, about 5 minutes. If the eggs start to sputter and bubble up, reduce the heat. When the eggs are ready use a spatula to remove the eggs from the pan onto a plate.
Place one of the cheese-topped slices on top of one of the pieces with the ham, cheese side up. Place one of the eggs on top. Repeat with the remaining sandwich. Serve immediately.