For this delicious French sandwich, sourdough bread is spread with a mornay sauce and Dijon mustard, stuffed with ham and cheese, and topped with a fried egg!
Ingredients
For the Mornay Sauce:
2tbspbutter(unsalted or salted)
2tbspall-purpose flour
1cupwhole milk
2.5ouncesgruyere cheeseshredded (1/2 cup measured)
pinch of nutmeg(preferably freshly grated)
salt
For the Croque Madame:
8slicessourdough bread
1/2lbblack forest hamthinly sliced from the deli
6ozgruyere cheesegrated (a heaping cup, measured)
2tbspdijon mustard
4tbspsoftened salted butter, for spreading(or more)
In a medium skillet, melt the butter over medium low heat. Add the flour and whisk until a smooth, blond paste forms, about 30 seconds.
While whisking, add 1/4 of the milk to start. Whisk until smooth, then gradually add in the rest of the milk, to minimize clumping. Bring to a boil, then reduce to a simmer and cook for 1-2 minutes, until the sauce thickens.
Remove the pan from the heat, then whisk in the gruyere, nutmeg, and 1/4 tsp salt, until smooth and gooey. Taste and add more salt, if necessary, then set the sauce aside.
To Make the Croque Madame Sandwiches:
For each sandwich, spread one slice with mornay sauce, and the other slice with Dijon mustard. I like about 1.5 tbsp of Mornay per slice, and 1.5 tsp of Dijon per slice, but no need to be exact.
Add a few slices of ham to one of the bread slices, and about 1/4 cup of shredded gruyere to the other. Put the bread slices together to form sandwiches, then spread the outsides of both pieces of bread with softened butter, about 1.5 tsp each, but again, no need to be exact.
Heat a nonstick frying pan over medium heat and cook the sandwiches on each side for 2-3 minutes, until golden brown on each side.
Remove the sandwiches to a sheet pan, and preheat the oven broiler to high.
Spread about 2 tbsp of mornay sauce onto the top of each sandwich, and broil until the tops are golden brown and bubbly, and the sauce has seeped into the crispy bread, about 2 minutes.
Fry the eggs in the same frying pan that you grilled the sandwiches with, making sure to season them well with salt and pepper, until the white is set but the yolk is still runny, about 2 minutes.
Top each sandwich with a fried egg, then enjoy while hot!
Notes
There's enough mornay sauce here for 4 hefty sandwiches, and you could possibly stretch it to 6. Also, you can choose to make only 1 or 2 sandwiches at a time, and keep the leftover mornay in the fridge for making additional sandwiches another day.Use a sturdy bread: I have tested tons of variations of this sandwich over the years, and though I commonly see white sandwich bread used, I recommend a sturdy loaf bread like sourdough.Leftovers: I don't recommend storing the egg, but the sandwiches keep well. Let cool to room temperature (to prevent sogginess), then store in an airtight container in the fridge for up to 5 days. You can also freeze for up to 2 months.Reheating: I don't recommend the microwave, as the sandwich will be soggy. Reheat in a 300F oven for 10-15 minutes, until warmed through.