EASY & SIMPLE CROQUE MONSIEUR RECIPE | FRENCH HAM & CHEESE SANDWICH

CROQUE MONSIEUR (2 SERVINGS) 4 slices of bread 8 slices of ham or mortadella (I use chicken mortadella) Gruyere or mozzarella cheese Dijon mustard Bechamel sauce: 2 tbsp butter 2 tbsp all-purpose flour 250ml milk 1/4 tsp salt & nutmeg