1. Cook the potatoes, then peel and slice them.
2. Slice the garlic cloves.
3. Melt the butter in a saucepan, add the garlic and 100g of Brie cheese.
4. Stir, then add the heavy cream.
5. Keep stirring.
6. Let it simmer on low heat.
7. Add the sliced potatoes to the butter-Brie-cream mixture in the saucepan.
8. Let it simmer for a few minutes.
9. Take out your gratin dish, put the mixture in it, season with salt and pepper.
10. Cut the remaining Brie and place it on top.
11. Bake in the oven for 20 minutes.