Refrigerate: Cover leftovers and chill up to 4 days. Reheat, covered, at 325°F (165°C) until hot, then uncover for 5 minutes to re-crisp the top.Freeze: Cool completely, wrap well, and freeze up to 2 months. Thaw overnight in the refrigerator and reheat as above.Make ahead: Assemble through step 4 up to 24 hours in advance. Cover and refrigerate. Add 10–15 minutes to the covered bake time if starting cold.
Why This Recipe Works
Heating the cream with butter and aromatics dissolves fat uniformly and jump-starts starch gelatinization, which sets the sauce into a velvety nap rather than a thin soup.
Layering cheese between the potatoes seasons every bite and stabilizes the sauce, while a final uncovered bake evaporates excess moisture and forms a savory browned crust.
Resting is crucial; it allows the starches to firm up, so slices stand tall on the plate.Expert Tips
Flavor boosters: Rub the dish with a cut garlic clove before buttering, or add a teaspoon of Dijon to the cream for gentle tang.
Cheese swap: Comté, Emmental, or sharp cheddar all work; keep Parmesan for the top for best browning.
Scaling: For two trays, double all ingredients and bake on separate racks, rotating pans halfway.
