Fresh Mushroom Clafouti

Ingredients

• 2 tablespoons corn oil margarine
• 3/4 cup onion, chopped
• 1 1/2 pounds white button mushrooms, thinly sliced
• 1/3 cup dry Sherry
• 1 1/3 cup skim milk
• 3/4 cup all-purpose flour, unbleached
• 3 large egg whites
• 1 large egg
• 1/2 tablespoon thyme leaves, crushed
• 1/4 tablespoon salt
• 1/4 tablespoon freshly ground black pepper
• 1/2 cup parmesan cheese, freshly grated