This Potato and Mushroom Gratin was the perfect side dish to serve with our Thanksgiving feast. I found the recipe using Epicurious’s handy iPhone application (which is free and so helpful!). The recipe makes enough to feed a small village. I made half and we still had plenty to eat for leftovers. Other than the fact that it is extremely heavy – parboiling anything in heavy cream is dangerous for one’s health.  It was  worth it, I guess, since it was Thanksgiving. I recommend this for a special occasion or a last meal.

Potato and Mushroom Gratin from November 2010 Bon Appetit

Ingredients:

• 1/4 cup olive oil
• 4 cups finely chopped leeks (white and pale green parts only; about 3 large)
• 1 1/2 pounds 1/2-inch cubes assorted mushrooms (such as crimini and stemmed shiitake; about 10 cups)
• 2 garlic cloves, minced
• 3 pounds Yukon Gold potatoes, peeled, cut into 1/8-inch-thick slices
• 2 cups heavy whipping cream
• 1 teaspoon (or more) salt
• 1/2 teaspoon (or more) freshly ground black pepper
• 1 cup coarsely grated Gruyère cheese

Heat 1/4 cup oil in large skillet over medium-high heat. Add leeks; sauté until soft and lightly browned, 10 to 12 minutes. Add mushrooms, sprinkle with salt and pepper, and sauté until soft and liquid evaporates, 7 to 8 minutes. Add garlic; sauté 1 minute. Season with salt and pepper. Set aside. DO AHEAD: Can be made 4 hours ahead. Let stand at room temperature.

Preheat oven to 375°F. Pat potato slices dry with kitchen towel. Combine cream, 1 teaspoon salt, and 1/2 teaspoon pepper in large pot. Add potatoes. Bring to boil; reduce heat to medium and simmer, covered, 10 minutes, stirring occasionally. Remove lid; simmer until cream is reduced by about half and potatoes are partially cooked, stirring often and watching closely to prevent mixture from burning, about 3 minutes. Season with salt and pepper.

Brush 13 x 9 x 2-inch glass or ceramic baking dish with oil. Transfer half of potato mixture to dish, spreading out in even layer. Spoon mushroom mixture over in even layer. Spoon remaining potato mixture over, spreading in even layer. Sprinkle cheese over. Cover with foil, tenting in center to prevent cheese from sticking to foil. Bake 30 minutes. Uncover; bake until potatoes are tender and top is brown, 20 to 25 minutes longer. Let rest 10 minutes before serving.