Potato, Leek, Gruyere, and Oyster Mushroom Gratin

I had this served to me the other night and the amount of comments generated from this dish made me think I needed to get the recipe. I am so glad that I did!! This does make a lot, but it can be cut in half for a smaller setting

• Ready In: 2 hrs 15 mins
• Serves: 10-12

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)

Directions

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