Step by step recipe:

1. 3 min.

   Prepare the bread

   
   Prepare 8 slices bread. If you are using a sandwich-type loaf or long French-style bread stick, leave the slices whole. If using a larger loaf, cut the slices in half (like in the photos).
2. 3 min.
   Melt 40 g butter, then use a brush to coat one side of the bread with melted butter.
   
   Arrange the slices on a baking sheet, buttered side downwards.
3. 10 min.

   Prepare the creamed leeks

   
   Prepare 3 leeks and chop finely.
4. 2 min.
   Prepare 1 shallot and chop finely.
   
   Pour 3 tablespoons olive oil into a large frying pan and when really hot, add the chopped shallot, salt and pepper.
   
   Cook for 1 minute without colouring.
5. 3 min.
   Add the chopped leeks, salt and pepper again and mix well.
   
   Cook for 1 or 2 minutes covered...
6. 7 min.
   ...then add 150 ml cream and leave uncovered on low heat to reduce.
7. 
   You should end up with a creamy leek "fondue" of fairly thick consistency.
   
   Set aside.
8. 5 min.

   Fry the ham

   
   Fry 4 slices smoked ham for 1 or 2 minutes on each side until nicely browned.
   
   Set aside.
9. 10 min.

   Fry the potatoes

   
   Slice 250 g cooked potato into thin rounds and pan-fry on both sides in 4 tablespoons olive oil.
10. 2 min.

    Assemble the croque-monsieurs

    Preheat the oven at 390°F (200°C).
    
    Arrange a layer of fried potatoes on half the slices of bread.
11. 3 min.
    Top with a layer of creamed leeks.
12. 2 min.
    Then a slice of fried ham.
13. 1 min.
    Finish by adding a second slice of bread, buttered side outwards.
14. 20 min.

    Brown the croque-monsieurs

    
    Cook the corque-monsieurs in the oven for about 20 minutes until the bread is nicely browned on top.
15. 
    Serve piping hot on its own or with a little lettuce "chiffonade".