Croque Monsieur

Make the Béchamel

Melt 2 tablespoons butter in a small saucepan over medium-low heat.

Add the flour to the melted butter and whisk constantly for 1 minute to cook out the raw flour taste.

Pour in the warm milk slowly in a steady stream, whisking continuously to prevent lumps.

Continue to whisk over medium-low heat until the sauce thickens to a spreadable consistency, about 3 minutes.

Remove from heat and stir in the nutmeg, salt, and black pepper.

Stir in 1/2 cup of the grated Gruyère until melted and smooth.

Prepare the Bread

Preheat the oven broiler to high and position a rack about 6 inches from the broiler element.

Place all 8 bread slices in a single layer on the baking sheet.

Toast the bread slices under the broiler for 1 to 2 minutes until just lightly golden, then remove from the oven.

Assemble the Sandwiches

Spread the softened butter evenly on one side of each toasted bread slice.

Flip 4 of the slices butter-side down and spread a thin layer of Dijon mustard on the upward-facing sides.

Layer 2 slices of ham onto each mustard-coated bread slice.

Sprinkle 2 tablespoons of the remaining grated Gruyère over the ham on each sandwich.

Place the remaining 4 bread slices on top, butter-side up, to close each sandwich.

Toast in the Pan

Heat a large skillet over medium heat.

Place 2 sandwiches at a time in the skillet and cook for 2 minutes per side until deep golden brown.

Transfer the toasted sandwiches back to the baking sheet and repeat with the remaining 2 sandwiches.

Add Topping and Broil

Spoon a generous layer of the béchamel sauce over the top of each sandwich.

Divide the remaining grated Gruyère evenly over the béchamel on each sandwich.

Broil the sandwiches for 2 to 3 minutes until the cheese is bubbling and golden brown with lightly charred spots.

Serve

Allow the sandwiches to rest for 1 minute, then slice diagonally and serve immediately.