1. Preheat oven to 400. 2. Arrange a 16 to 18 inch square of aluminum foil on a flat work surface. 3. Wash the mushrooms and drain well then pile them in center of foil and sprinkle with salt, pepper and garlic. 4. Dot with butter then sprinkle with the oil. 5. Gather up the edges of the foil and fold them together securely to encase the mushrooms in a square package then place foil package seam side up on a cookie sheet and bake 45 minutes. 6. Unwrap the package and serve mushrooms in their own juices with a sprinkling of parsley on top.
