Step by step recipe:

1. 4 min.
   Peel 500 g onion.
2. 5 min.
   Slice thinly.
3. 2 min.
   Melt 50 g butter in a frying pan on medium heat, then add the sliced onions, salt and pepper.
4. 7 min.
   Fry until just starting to brown.
   
   Set aside.
5. 5 min.
   Using the same pan, pour in 1 tablespoon olive oil.
   
   When very hot, add 200 g small pieces of bacon and fry as you like it.
6. 1 min.
   When the bacon is cooked, add the onions and mix well.
7. 3 min.
   Add 2 tablespoons cream, mix well, leave for a few minutes to thicken, then check the seasoning.
8. 1 min.
   Preheat the oven to 390°F (200°C).
   
   Use a round tin, preferably spring-form or loose bottomed. Scatter a little grated cheese in the bottom.
9. 1 min.
   Lay a pancake in the tin, trimming the edges if it doesn't fit.
10. 1 min.
    Spread a little of the onion-bacon-cream filling on top.
11. 7 min.
    Add another pancake and repeat the operation until you have used up all the pancakes and filling.
12. 1 min.
    Finish with a little grated cheese.
13. 30 min.
    Bake for about 20 to 30 minutes...
14. 
    ...until the top pancake is nicely browned.
15. 1 min.
    Turn out upside down and serve hot, cut into portions like a pie.