1/2 cup (125 milliliters) shredded mozzarella cheese, divided
1 tablespoon (15 milliliters) unsalted butter
2 large eggs
In a medium saucepan, melt the butter over medium heat. Sprinkle the sage and flour over the melted butter and whisk for about one minute, until a paste forms. Turn the heat up to medium-high and slowly pour in the milk while constantly whisking.
Continue to cook, whisking, as the sauce thickens. Turn the heat back down to medium, add the Parmesan, and whisk until melted. Remove from the heat.
Preheat the oven to 400 degrees Fahrenheit (200 degrees Celsius). Lay the bread on a cutting board and spread a thin layer of mustard over each slice. Lay one slice of ham on each piece of bread. Sprinkle 1/4 cup (60 milliliters) mozzarella on each of two slices of bread. Close the sandwiches, then use a five centimeter round cookie cutter or a glass to cut out the centre of each sandwich Do not discard the mini centre sandwiches.
In an ovenproof frying pan, melt the butter over medium-high heat. Fry sandwiches (and the mini sandwiches!) for one minute, or until golden brown and crispy. Flip the sandwiches.
Crack an egg into the hole of each large sandwich. Place the whole pan in the oven and bake for 12 to 15 minutes, or until the eggs are set to your liking.
Remove the pan from the oven. Switch the oven to broil. Spoon the Béchamel Sauce over the sandwiches. Return the whole pan to the oven and broil for two to three minutes, or until the Béchamel Sauce is golden and bubble.
Serve this very French sandwich with a side of creamy Dijon mustard and baby cornichons. Merci.