A recipe for an open-faced croque monsieur: A toasted ham sandwich with a Gruyere cheese sauce
The first time I laid eyes on the Croque Monsieur, it was love at first sight and I thought to myself, “What is that sandwich calling my name with the luscious, cheesy situation on top…and, how in the world does a sandwich know my name?” Of course, I jest. It was a cheesy joke. I know. Pun intended. Ok, I’ll stop now. I know it sort of kinda sounds like I wanted to date my lunch, but in truth, it was the beginning of a love affair.
When you’re in the mood for a souped-up, fancy-pants ham and cheese sandwich, I promise, the croque monsieur’s got your cravings covered. It begins with a creamy mornay sauce, laden with perfect, stretchy Gruyere cheese. Since this recipe began with leftover Easter Ham in mind, I felt an open-faced sandwich would be better suited for thick-cut slices of protein. Two pieces of bread isn’t really necessary for this level of decadence anyhow. Lastly, a little whole grain mustard to add some zing and cut through the richness, and ohh la la, I think it’s high-time you braced yourselves for a love-at-first-bite affair with this little French number.
- 4 1/2 - 3/4" slices white bakery bread
- 2-3 tablespoons room temperature unsalted butter for spreading + plus 3 tablespoons more, separated
- 3 tablespoons all-purpose flour
- 2 cups whole milk warmed
- 1 1/2 cup freshly grated Gruyere cheese preferably Boars Head, separated
- 1/4 cup freshly grated Parmesan cheese
- 1/2 teaspoon Kosher salt
- Generous pinch black pepper
- 10 ounces thick-cut ham torn or cut into large chunks
- 1/3 - 1/2 cup of whole-grain mustard
- 2 tablespoons minced chervil Italian flat-leafed parsley
Preheat the oven to 425° and have ready a sheet pan lined with aluminum foil.
Place a medium-sized skillet over medium-low heat. Spread a thin layer of butter evenly across both sides of each slice of bread. Place slices of bread on skillet, taking care not to overcrowd the pan, and allow to toast for 1 1/2 - 2 minutes or until golden brown. Flip and repeat on other side. Set aside on a wire rack until ready to use.
Add 3 tablespoons of butter to the same skillet and allow to melt. Immediately after butter has melted, sprinkle in flour and whisk until a paste has formed, 1-2 minutes. Add milk, one generous splash at a time, and whisk after each addition until the mixture begins to resemble a pudding-like texture. At this point, add the remaining milk in a small stream, whisking all the while. Increase the heat to medium-high, and allow the mixture to rapidly simmer 3-5 minutes, until slightly thickened, stirring often. Remove from the heat and stir in 1 cup of Gruyere cheese, Parmesan cheese, salt and pepper. Set aside until ready to use.
Place each piece of toast across the sheet pan, spacing them at least 1" apart. Spread with a generous smear of whole-grain mustard. Divide ham amongst the toast. Place a generous dollop of cheese sauce on top of the ham and spread to cover. Divide the remaining Gruyere, and sprinkle across the sandwiches.
Bake for 12 minutes, or until the cheese has melted and begins to bubble. Remove from the oven, sprinkle with chervil or parsley, if desired, serve and enjoy.
Would pair well with: