1. Cook the crozets in boiling salted water for 20 minutes.
2. After 10 minutes of cooking the crozets, chop the onion and sauté it in butter. Let it caramelize.
3. Set the onions aside and sauté the bacon.
4. Put the cooked onions, bacon, and cream in the pan and let it reduce.
5. Drain the crozets.
6. In a gratin dish, layer the crozets, then a layer of cream/bacon/onions.
7. Fill the dish in this manner and place the reblochon cheese cut in half on top.
8. Bake in the oven for 20 minutes at 200°C.