Position a rack in the center of the oven and heat the oven to 350°F. Butter a 9x13-inch (or similar) baking dish.
In a 5-quart pot, bring the milk, cream, nutmeg, and garlic to a boil over medium-high heat. Reduce the heat to medium low and simmer 5 minutes, stirring occasionally, to infuse.
Meanwhile, melt the butter and pour into a medium bowl. Add the breadcrumbs and Gruyère and toss.
Stir the potatoes, 1-1/2 Tbs. salt, and 1/2 tsp. pepper into the milk mixture, raise the heat to medium high, and return just to a boil. Carefully transfer the potato mixture to the prepared dish and spread out evenly. Scatter the breadcrumb mixture over the top and bake until the potatoes are tender when pierced with a fork, and the breadcrumbs are golden-brown, about 45 minutes.
Let rest 15 minutes before serving.
- For a sweeter gratin, substitute sweet potatoes for half of the potatoes.
- Instead of infusing the cream with nutmeg and garlic, whisk in 1 to 2 Tbs. of adobo (from a can of chipotles in adobo) for a little heat.
- Make it extra cheesy: Put half of the potato mixture in the casserole dish, then add an extra cup of Gruyère before adding the rest of the potatoes and the topping.
nutrition information (per serving):
21, Fat Calories
190, Saturated Fat
9, Monounsaturated Fat
34, Polyunsaturated Fat
Photo: Scott Phillips