Ingredients
Equipment
Method
- Heat the oven to 375°F and grease a 9x13-inch baking dish with the butter.
- Warm the heavy cream, milk, garlic, thyme, salt, and pepper in a saucepan over medium heat until steaming, about 3 to 5 minutes; do not let it boil.
- Slice the potatoes, parsnips, and carrots into 1/8-inch-thick rounds.
- Arrange the vegetables in overlapping layers in the prepared dish, mixing them as you go.
- Pour the warm cream mixture evenly over the vegetables and sprinkle the Gruyère over the top.
- Cover the dish tightly with foil and bake for 55 to 65 minutes, until a knife slides easily into the center.
- Uncover and bake for 20 to 25 minutes more, until golden and bubbling.
- Let the gratin rest for 15 minutes before serving.
Notes
For even cooking, slice the vegetables uniformly to 1/8 inch thick. Refrigerate leftovers for 3 to 4 days; freezing is not recommended because the cream sauce may separate. For a lower-lactose version, use lactose-free cream and milk and a suitable aged cheese.
