First, make the white sauce. Melt the butter in a pan over a low heat, then add the flour and cook for 5 minutes, stirring regularly. Meanwhile, heat the milk gently in a separate pan – do not let it boil. Pour the milk little by little into the flour and butter mix, stirring all the time – keep the heat low so the sauce doesn’t catch and burn on the bottom of the pan.

Season with salt and pepper and bring the sauce to a slow simmer. Continue to cook for 5 minutes over a low heat, stirring constantly. It should be lump-free, but if there are any lumps, pass the sauce through a fine sieve.

Toast the slices of bread on one side and butter the toasted side. Lay the slices of ham on the toasted side of 4 of the slices and dab with a little mustard. Spread on some of the white sauce and add some cheese and a little more white sauce. Top with the rest of the slices of toast, toasted and buttered side down, and sandwich together, pressing lightly. Then toast one side under a hot grill, turn it over, add more white sauce and cheese and grill the top until golden.

While the sandwiches are toasting, fry the eggs.

Place a non-stick frying pan over a medium heat and add enough vegetable oil to cover the bottom of the pan. Crack in the eggs one by one and season with salt and pepper. Fry for 3-4 minutes, depending on how you like your eggs done. If you want the yolk cooked more firmly, spoon over a little of the hot oil for a few minutes. Add the eggs to the croques.