Croque Madame with Mustard Béchamel

Ingredients

• 4 slices pain de mie or good sandwich bread
• 4 oz ham, thinly sliced
• 1½ cups grated Gruyère
• 2 tbsp butter
• 2 tbsp flour
• 1 cup whole milk
• 1 pinch nutmeg
• 2 eggs
• 1 tsp Dijon mustard
• Salt and white pepper

Method

1. Make the béchamel: melt 1 tablespoon butter, whisk in the flour, cook 1 minute, then add the milk gradually. Simmer until it thickly coats a spoon; season with nutmeg, salt, and white pepper.
2. Spread the bread with Dijon, layer ham and half the Gruyère between the slices, and close the sandwiches.
3. Spoon béchamel generously over the tops, blanket with the remaining Gruyère, and bake at 425°F (220°C) for 8–10 minutes until bubbling, finishing under the broiler until leopard-spotted.
4. Meanwhile, fry the eggs in the remaining butter, keeping the yolks glossy and loose.
5. Crown each sandwich with an egg — madame's hat — and serve with a knife, a fork, and a green salad for plausible deniability.