Wild Mushroom and Potato Gratin

Preparation

1. Step 1

   Place the dried porcinis in a bowl or a pyrex measuring cup and pour on 1½ cups boiling water. Soak for 30 minutes. Line a strainer with cheesecloth and place over a bowl. Drain mushrooms, then squeeze in cheesecloth to extract juices. Rinse several times and chop medium-fine. Measure out 1 cup of broth.

2. Step 2

   Meanwhile heat oven to 375 degrees. Rub inside of a 3-quart gratin dish or baking dish all over with the cut half garlic clove and lightly oil with olive oil. Heat oil in a wide, heavy nonstick skillet over medium heat. Add onion or shallots and cook gently until just tender, 3 to 5 minutes. Turn up heat to high and add mushrooms. Cook, stirring, until they begin to sweat, 2-3 minutes, reduce heat to medium, and add minced garlic, thyme, rosemary or sage and dried porcinis. Cook, stirring, until fragrant, about 30 seconds. Season mushrooms with salt and pepper and continue to cook over medium heat until soft, about 5 more minutes. Add wine and cook, stirring, until it is no longer visible in the pan. Taste and adjust seasoning.

3. Step 3

   In a large bowl combine potatoes, mushrooms, half the cheese, and salt and pepper. Arrange in an even layer in gratin dish.

4. Step 4

   Combine milk and mushroom broth. Season generously with salt and pour over the potatoes and mushrooms. Press the vegetables down into the liquid. Bake 1 hour. Every 20 minutes remove gratin dish and press potatoes and mushrooms down into the liquid with the back of a large spoon. After 1 hour, sprinkle on remaining cheese and bake for another 30 minutes, until top is golden and the sides crusty. Remove from the oven and allow to sit for 10 to 15 minutes before serving. Serve hot or warm.