1 oz. dried porcini mushrooms
1 c. warm water
5 lbs. all-purpose potatoes
3 tbsp. butter
1 1/2 lbs. fresh mushrooms, sliced
2 c. heavy or whipping cream
1 c. milk
2 tsp. salt
1/2 tsp. freshly ground pepper
Pinch nutmeg
2 c. (8 oz.) grated Gruyere cheese

In small bowl soak porcini mushrooms in warm water 30 minutes. Remove mushrooms from liquid; rinse thoroughly and chop. Strain liquid through coffee filter or sieve lined with paper towel.

Meanwhile, peel potatoes and slice 1/8-inch thick. Let stand in large bowl of cold water.

Preheat oven to 425 degrees. In large skillet melt butter over high heat. Add fresh and porcini mushrooms; saute until browned and liquid evaporates, 10-15 minutes. Drain potatoes and pat dry on kitchen towels. Spread evenly in 2 (13 x 9) baking pans.

In medium saucepan combine cream, milk, mushroom soaking liquid, salt, pepper, and nutmeg. Bring to a boil; pour evenly over potatoes. Sprinkle with mushrooms, then cheese. Bake 40-45 minutes, until potatoes are tender and most liquid is absorbed. (If pans are on 2 racks, switch positions halfway through cooking.) Makes 16 servings.