Fry the crushed garlic lightly in a good knob of butter and some virgin olive oil.
Add sliced potatoes. Cook in the butter until all the potatoes are covered with the butter and oil.
Season with freshly grated nutmeg (this is very important)
Add salt and black pepper
Start cooking on top of the cooker
Add more butter.
When potatoes are a bit soft, put in a casserole dish
Place in oven with some knobs of butter here and there on top.
Cook SLOWLY for around 2 hours until golden brown.
Make sure the potatoes are cooked before turning off the oven.
Test with a skewer.
If you like you can add grated cheese, although it's not really part of the recipe.
This one came from France too.