Herbed Potato & Sweet Potato Gratin

Herbed Potato & Sweet Potato Gratin

Sides
Potatoes, Sweet Potatoes, Holidays

Serves 10-12

This gratin makes a great Thanksgiving side dish if you want a more savory sweet potato dish that even sweet potato haters will love.

Ingredients #

  • 1 1/2 lbs medium Yukon Gold potatoes
  • 1 1/2 lbs medium sweet potatoes
  • 2 cups heavy cream
  • 1/4 cup butter
  • 2 garlic cloves, minced
  • 1 tbsp minced fresh parsley
  • 1 tbsp minced fresh rosemary
  • 1 tbsp minced fresh sage
  • 1 tbsp minced fresh thyme
  • 1 1/2 tsp salt
  • 3/4 tsp freshly ground black pepper
  • 1 1/4 cup (5 ounces) grated Gruyere cheese
  • 1/3 cup grated Parmeggiano Regiano (optional)

Instructions #

Preheat oven to 300°F.

Peel the potatoes and sweet potatoes, and slice them into 1/8” rounds.

Combine the cream, butter and garlic in a medium saucepan and bring just to a simmer. Reduce heat to very low, and keep just short of a simmer. Mix the minced herbs in a small bowl. If using Parmeggiano Regiano cheese, toss it with the shredded Gruyere to combine.

Butter 13x9x2-inch glass baking dish. Pat the potato slices dry with paper towels. Lay potato and sweet potato slices (at random, or in alternating rows, or in alternating layers). Lightly season each layer with salt and pepper, sprinkle generously with minced herbs, and sprinkle on a large pinch of cheese (this takes some practice to get right — you want just enough to “glue” the layers together and give good flavor, but too much cheese will make the gratin greasy). Reserve a little of these items for the top of the gratin.

Pour the cream mixture over the gratin, pressing the solids down lightly. Season the top with salt and pepper, the remaining herbs and the remaining cheese.

Place the gratin in the middle of the preheated oven and bake until the potatoes are quite tender and the top is beautifully browned. This might take two hours or a bit more, so give yourself time. The key here is to regulate the heat so that the cream just slowly bubbles — if it simmers constantly, the cream will break.

Let the gratin stand for at least 10-15 minutes (and up to 30) to allow it to come together.