Recipe from Ina Garten, The Barefoot Contessa Cookbook. I doubled the recipe and decreased the cooking time to 1 hour; heating them up later before the party.
2small fennel bulbs
1yellow onion, thinly sliced
2tablespoonsgood olive oil
2poundsrusset potatoes, 4 large potatoes
2cupsplus 2 tablespoons heavy cream
2 1/2cupsgrated Gruyère cheese, 1/2 pound
1/2teaspoonfreshly ground black pepper
Preheat the oven to 350 degrees F.
Butter the inside of a 10-by-15-by-2-inch (10-cup) 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 4 cups of sliced fennel. Saute the fennel and onions in the olive oil and butter on medium-low heat for 15 minutes, until tender.
Peel the potatoes, then thinly slice them by hand or with a mandoline. Mix the sliced potatoes in a large bowl with 2 cups of cream, 2 cups of Gruyère, salt, and pepper. Add the sauteed fennel and onion and mix well.
Pour the potatoes into the baking dish. Press down to smooth the potatoes. Combine the remaining 2 tablespoons of cream and 1/2 cup of Gruyère and sprinkle on the top. Bake for 1 1/2 hours, until the potatoes are very tender and the top is browned and bubbly. Allow to set for 10 minutes and serve.