Makes 8-10 servings. Difficulty
1/2 pounds shiitake mushrooms, trimmed and coarsely chopped 2-1/2 Tablespoons unsalted butter 3/4 pounds cremini mushrooms, stemmed and sliced 1 large garlic clove, minced 3 pounds russet potatoes, peeled and cut into 1/8-inch thick slices 1 garlic clove, roasted 1 cup cream 1 cup milk Salt and freshly ground black pepper Dash of fresh nutmeg 2 ounces grated gruyère 2 ounces grated white cheddar cheese
Preheat oven to 400°F. Position rack in middle of oven.
Butter a 3 quart shallow baking dish.
In a large skillet heat 1 tablespoon butter over medium heat. Add shiitakes and half the minced garlic; sauté for about 8 minutes or until tender and most of the liquid given off by the mushrooms has evaporated.
Transfer shiitake mushrooms to a bowl. Add remaining 1-1/2 tablespoons butter to skillet. Add cremini mushrooms and remaining minced garlic; sauté for about 8 minutes, or until tender and the liquid generated by the mushrooms evaporates.
Transfer cremini mushrooms to bowl with shiitakes. Season mushrooms with salt and freshly ground black pepper.
In a large saucepan bring sliced potatoes, roasted garlic, cream, milk, 1-1/2 teaspoons salt, 1/2 teaspoon freshly ground black pepper and a dash of fresh nutmeg to a boil. Stir a couple of times, then remove from heat.
Using a slotted spoon, transfer half the potatoes to baking dish, spreading evenly. Spread mushrooms over potatoes. Sprinkle with half the gruyère and half the white cheddar. Top with remaining potatoes. Pour the cooking liquid over the potatoes and sprinkle with remaining gruyère and white cheddar.
Bake until top is golden brown and potatoes are tender, about 45-55 minutes. Let stand for 10 minutes before serving.