Step by step recipe:

1. 5 min.
   Chop 2 shallots.
2. 2 min.
   Melt 2 tablespoons goose fat in a frying pan.
3. 3 min.
   Put in 1 kg 500 g cooked potato sliced, in a single layer.
4. 10 min.
   After 5 minutes turn over potato slices, and cook until golden brown.
   
   Don't salt at this stage, otherwise your potatoes will stick.
5. 5 min.
   Put onto absorbant paper to remove the excess fat.
   
   Repeat operation until all potatoes are cooked.
6. 2 min.
   Clean the frying pan, melt the remaining fat, add chopped shallots, salt and pepper, and cook 1 or 2 minutes.
7. 1 min.
   Add 100 g small pieces of bacon.
8. 4 min.
   And cook for a further 3 or 4 minutes.
   
   Note: Everything so far can be prepared in advance (the day before or so). But what follows must be done at the last minute for a better and crusty result.
9. 2 min.
   Put cooked potato slices back in the frying pan.
10. 5 min.
    Mix well and reheat on medium heat.
11. 1 min.
    Taste and adjust seasoning.
12. 
    It's ready !
    
    Serve piping hot, alone or with a good green salad.