Oyster Mushroom and Potato Gratin

1 oz. dried oyster mushrooms or 4 oz. fresh oyster mushrooms
5 potatoes, peeled & sliced
2 Tbsp. butter
1/2 cup chopped onion
8 oz. cream cheese, cubed
1 cup heavy cream
1 cup milk
1/2 tsp. salt
1/4 tsp. black pepper
6 slices bacon, cooked and crumbled

If using dried mushrooms, reconstitute by soaking in warm water. Slice mushrooms into bite-sized pieces. Preheat oven to 350 degrees. In 2 qt. saucepan, melt butter over medium-high heat. Add onion; saute' until tender. Add cream cheese, cream, milk, salt and pepper. Heat until cheese melts, stirring often. In large bowl, combine potatoes, mushrooms, bacon and cream cheese mixture. Spoon into greased 2 qt. casserole. Cover. Bake 1 hour or until potatoes are tender.