Serves: Makes 6 to 8 servings
- 2½ cups whole milk
- 1½ cups heavy cream
- 2 teaspoons coarse salt
- 2 teaspoons minced fresh rosemary
- 1 clove garlic, grated or finely chopped
- ⅛ teaspoon freshly ground black pepper
- 2 pounds Yukon Gold potatoes, peeled and sliced ¼ inch thick
- 2 pounds sweet potatoes, peeled and sliced ¼ inch thick
- ½ teaspoons unsalted butter, softened
- ½ cup shredded Gruyère cheese
- ½cup shredded white Cheddar cheese
- ½ cup grated Parmigiano-Reggiano cheese
Procedures:Potato gratins are classic, but the combination of yellow Yukon Gold potatoes and orange sweet potatoes is novel. Rosemary gives the creamy sauce a distinctive profile that goes well with big flavors like grilled salmon, steaks, or lamb chops.
- In a large heavy pan, combine the milk, cream, salt, rosemary, garlic, and pepper. Place over medium heat and heat, stirring, for 3 minutes, or until small bubbles appear around the edges of the pan. Add the Yukon Gold and sweet potatoes, stir to coat, and simmer gently, uncovered, for 10 to 12 minutes, until the potatoes are partially cooked. Remove from the heat.
- Preheat the oven to 400°F. Rub the butter over the bottom and sides of a 2-quart gratin dish.
- Use a slotted spoon to transfer half the potatoes to the gratin dish. Sprinkle with half each of the Gruyère, Cheddar, and Parmigiano-Reggiano cheeses. Add the remaining potatoes. Use two forks to arrange the top layer of potatoes in a slightly overlapping design, evenly distributing the different-colored potatoes. Ladle the hot cream mixture over the potatoes and sprinkle with all of the remaining cheeses.
- Bake for 35 minutes, or until the potatoes are tender when pierced with a skewer or the tip of a knife and the gratin is bubbling and golden.
- Let the gratin rest for 10 minutes before serving.