This is from Melissa Clark’s new cookbook Dinner in French. I made a few minor changes including cutting the recipe in half. It is ridiculously rich and sinful.
4 tbsp butter
1/4 c flour
2.5 c milk
2.5 c grated Gruyere
1/2 tsp herbs de Provence
Pinch of nutmeg
8 slices white sandwich bread
6 oz thinly sliced ham
Heat oven to 375 and spray a 9×9 baking dish.
Melt butter in a medium skillet over medium heat. Stir in flour and cook, whisking, until it turns golden, about 3 minutes. Slowly whisk in milk and whisk until smooth. Stir in herbs, salt and 1 cup of cheese . Whisk till smooth.
Slather bread with mustard, top with ham, shredded cheese and another slice of bread.
Spread a small amount of sauce on the bottom of the baking dish. Place sandwiches in and top with sauce and any remaining cheese.
Bake for 30 – 40 minutes until brown and bubbling.