Cheesy Potato, Leek and Mushroom Gratin
A delicious combination of leeks, mushrooms and potatoes topped with cheese and baked until crusty on top yet creamy underneath.
1/2 stick, or half olive oil and half butter
white or cremini, sliced
thinly sliced (white and pale green parts only)
chicken broth, low salt
peeled, thinly sliced into rounds
grate, about 10 ounces
Melt 2 tablespoons butter (or 1 tablespoon olive oil, 1 tablespoon butter) in heavy large skillet over medium-high heat.
Stir in mushrooms and sauté until almost tender, 4 to 6 minutes.
Stir in garlic and sauté until mushrooms are tender and golden, about 3 minutes longer.
Transfer mushroom mixture to bowl.
Melt remaining 2 tablespoons butter (or half olive oil, half butter) in same skillet over medium-high heat.
Stir in leeks and thyme and sauté until leeks are tender and beginning to brown, 7 to 9 minutes.
Add leek mixture to bowl with mushrooms. (Can be made 1 day ahead. Cover and refrigerate.)
Preheat oven to 400°F.
Butter 13 x 9 x 2-inch baking dish.
Combine broth, cream, wine, 1 teaspoon salt and ½ teaspoon pepper in large bowl, whisk to blend.
Layer ⅓ of potatoes on bottom of prepared dish.
Top with half of mushroom-leek mixture, then ¾ cup cheese.
Top with half of remaining potatoes.
Pour half of cream mixture over.
Top with remaining mushroom-leek mixture and ¾ 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.