Gratin Dauphinois

Instructions

1. 1
   Preheat your oven to 160°C (320°F) with top and bottom heat.
2. 2
   Prepare the baking vessel: Take a rectangular white ceramic baking dish (similar to the one in `gratin dauphinois_2.png`) and rub the inside surface vigorously with the cut halves of one garlic clove. Next, grease the dish thoroughly with the 30g of unsalted butter.
3. 3
   Using a mandoline or a very sharp chef's knife, slice the peeled potatoes into rounds roughly 2 to 3mm thick. Crucial step: Do not rinse the potato slices under water after cutting, as we need their natural surface starch to bind the cream.
4. 4
   In a medium saucepan, combine the heavy cream, whole milk, the second minced garlic clove, salt, black pepper, and a generous pinch of freshly grated nutmeg. Bring to a bare simmer over medium heat.
5. 5
   Carefully drop the potato slices into the warm cream mixture. Simmer gently over very low heat for 8-10 minutes, stirring delicately so the slices don't break. This par-cooks them and activates the starches.
6. 6
   Using a slotted spoon, transfer the potato slices into the buttered baking dish, flattening and overlapping them evenly in horizontal rows.
7. 7
   Pour the remaining warm liquid cream mixture from the saucepan evenly over the arranged potatoes until they are mostly submerged, leaving the topmost layer slightly exposed.
8. 8
   Bake at 160°C (320°F) for 50-60 minutes. The low temperature allows the potatoes to become incredibly tender. During the final 10 minutes, turn the oven up to 200°C (400°F) or toggle the broiler to achieve that gorgeous, blistered, deeply golden-brown surface captured in the image.
9. 9
   Remove the gratin from the oven, scatter an extra dust of fresh cracked black pepper over the top, and let it rest for 10-15 minutes before carving; this sets the cream into its signature melt-in-the-mouth texture.