Croque-madame with Parma ham and Gruyère

Method

1. Spread the sourdough bread with Dijon mustard. Top each with 2 slices of Parma ham, a few slices of Gruyère and another slice of sourdough each, pressing down well.
2. Melt the butter with the olive oil in an ovenproof frying pan, fry the sandwiches for 2 minutes on each side, then pop into a preheated oven at 180°C/fan160°C/gas 4 for 5 minutes. Fry the eggs, serve with the sandwiches and finish with a good grinding of black pepper.