Potato, Leek, Gruyere, And Oyster Mushroom Gratin - cooking recipe

Ingredients

4 tablespoons butter
1 lb oyster mushroom, halved if large
1 tablespoon garlic, minced
4 cups leeks (white and pale green parts only, about 4 large, thinly sliced)
1 tablespoon fresh thyme, minced
1 3/4 cups chicken broth
1 3/4 cups whipping cream
1/4 cup dry white wine
1 teaspoon salt
1/2 teaspoon black pepper
3 3/4 lbs russet potatoes, peeled, thinly sliced into rounds (about 8 cups)
2 1/2 cups gruyere cheese, grated (about 10 ounces)

Preparation

Melt 2 tablespoons butter in heavy large skillet over medium-high heat. Add mushrooms and saute until almost tender, about 5 minutes. Add garlic and saute until mushrooms are tender and golden, about 3 minutes longer.
Transfer mushroom mixture to bowl. Melt remaining 2 tablespoons butter in same skillet over medium-high heat. Add leeks and thyme and saute until leeks are tender and beginning to brown, about 8 minutes.
Add leek mixture to bowl with mushrooms. (Can be made 1 day ahead. Cover and refrigerate.).
Preheat oven to 400\u00b0F Butter 13x9x2-inch baking dish. Whisk broth, cream, wine, 1 teaspoon salt and 1/2 teaspoon pepper in large bowl to blend.
Layer 1/3 of potatoes on bottom of prepared dish. Top with half of mushroom-leek mixture, then 3/4 cup cheese. Top with half of remaining potatoes.
Pour half of cream mixture over. Top with remaining mushroom-leek mixture and 3/4 cup cheese.
Cover with remaining potatoes. Pour remaining cream mixture over; sprinkle with remaining cheese.
Bake gratin uncovered until potatoes are tender and sauce bubbles thickly, about 1 hour 20 minutes. Let gratin stand 30 minutes before serving.