Cheese potatoes au gratin

 

• 1 yellow onion, thinly sliced
• 2 tablespoons good olive oil
• 1 tablespoon unsalted butter
• 2 pounds russet potatoes (4 large potatoes)
• 2 cups plus 2 tablespoons heavy cream
• 2 1/2 cups grated Gruyère, or cheddar cheese (1/2 pound)
• 1 teaspoon salt
• 1/2 teaspoon freshly ground black pepper
• 1 cup of diced Ham (optional)

1.Preheat the oven to 350 degrees F.
2.Butter the inside of a 10-by-15-by-2-inch (10-cup) baking dish.
3.Saute the onions in the olive oil and butter on medium-low heat for 15 minutes, until tender. 4.Peel the potatoes, then thinly slice them by hand or with a mandoline. 5.Mix the sliced potatoes in a large bowl with 2 cups of cream, 2 cups of Gruyère, salt, and pepper. Add the sauteed onion and mix well. 6.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 cheese and sprinkle on the top. Bake for 1 1/2  to 2 hours, until the potatoes are very tender and the top is browned and bubbly. Allow to set for 10 minutes and serve.