Potato Au Gratin

Preheat the oven to 190C. Coat a baking dish evenly with 1 tablespoon butter, then rub the buttered surface with 2 garlic cloves so the aroma begins underneath the potatoes. Trim and slice the potatoes into thin rounds. Uneven slices leave thick pieces firm while thin ones collapse during the same bake. Combine 300 ml heavy cream, 150 ml milk, 1 teaspoon salt, and 1/2 teaspoon black pepper. For a stronger garlic aroma, warm this mixture gently over low heat only until steaming; do not boil it. Arrange one slightly overlapping layer of potatoes in the dish, spoon over a thin layer of cream, and scatter on part of the 180 g Gruyere. Repeat the same sequence, reserving a generous share of cheese for the surface. Cover the dish with foil and bake for 35 minutes. Remove the foil when the cream bubbles at the edges and a skewer enters the potatoes with only slight resistance. Continue uncovered for about 15 minutes, until the cheese on top becomes deep golden and crisp. Rest the gratin for 10 minutes after it leaves the oven. During this time, the cream between the potato layers thickens and settles, allowing clean portions to be cut without the sauce immediately running across the plate.