Potato-Fennel Gratin

• 2 small fennel bulbs
• 1 yellow onion, thinly sliced
• 2 tablespoons olive oil
• 1 tablespoon unsalted butter
• 2 lbs russet potatoes (about 4 large)
• 2 cups heavy cream, plus
• 2 tablespoons heavy cream
• 2 1/2 cups gruyere cheese, grated (1/2 pound)
• 1 teaspoon kosher salt
• 1 teaspoon black pepper

1. Preheat oven to 350.
2. Butter inside of a 10x15x2-inch (10 cup) baking dish.
3. Remove stalks and core of fennel, slice thinly crosswise.
4. Saute fennel and onions in the olive oil and butter on Medium heat for about 15 minutes or until tender.
5. Peel potatoes, slice thinly.
6. Mix potatoes in a bowl with 2 cups cream and 2 cups Gruyere, salt, pepper and the sauteed onion/fennel mixture.
7. Pour into baking dish, press down to smooth.
8. Combine remaining 2 tbl cream and 1/2 cup Gruyere and sprinkle on top.
9. Bake for 1 1/2 hours until potatoes are very tender, the top is browned and bubbly.
10. Let set for 10-15 minutes before serving.

fennel bulbs, yellow onion, olive oil, unsalted butter, potatoes, heavy cream, heavy cream, gruyere cheese, kosher salt, black pepper

Taken from www.food.com/recipe/potato-fennel-gratin-75679 (may not work)