-Preheat your oven to 400 degrees.
-Melt butter in a small saucepan over low heat. Stir in the flour. Continue to stir for two minutes.
-Microwave the milk for 90 seconds on HIGH. Slowly pour the milk into the butter/flour mixture,
whisking constantly, until thickened.
-Remove saucepan from the heat. Whisk in the salt, pepper, nutmeg, Parmigiano Reggiano and 1/4 cup of
the grated Gruyere. Set aside.
-Cut the croissants in half and place onto a baking sheet, with the cut side up. Toast for 3 minutes in your
preheated oven, then flip the slices over and toast for an additional 2 minutes.
-Lightly brush one of the halves of each mini croissant with the dijon mustard.
-Add a slice of the thinly sliced ham.
-Sprinkle with about half of the remaining Gruyere. Top with the remaining croissant halves.
-Spoon a heaping tablespoon of sauce onto the top of each croissant. Sprinkle the remaining Gruyere on top.
-Bake for 5 minutes to melt the cheese, then place the sandwiches under the broiler for 3 minutes,
until the cheese is bubbly and lightly browned. Serve immediately.