Potato-Fennel Gratin (half-recipe)

Preheat the oven to 350 degrees. Butter a 9x9x2-inch baking dish.

Remove the stalks from the fennel and cut the bulbs in half lengthwise. Remove the cores and thinly slice the bulbs crosswise, making approximately 2 cups of sliced fennel. Sauté the fennel and onions in the olive oil and butter on medium-low heat for 10 to 15 minutes, until tender.

Peel the potatoes, then thinly slice them by hand or with a mandoline. Mix the potatoes in a large bowl with 1½ cups of the cream, 1 cup of the Gruyère, ½ teaspoon salt, and ¼ teaspoon pepper. Add the sautéed fennel and onion and mix well.

Pour the potatoes into the baking dish. Press down to smooth the potatoes. Combine the remaining 1 tablespoon of cream and ½ cup of Gruyère and sprinkle on the top. Bake for 1 hour, until the potatoes are very tender and the top is browned and bubbly. Allow to set for 10 minutes and serve hot.