Remove and discard mushroom stems. Wash mushroom caps and pat dry; set aside. Combine bread crumbs, crabmeat, Parmesan
cheese, bell peppers, scallions, thyme and pepper in a medium-sized
bowl and mix well.
Add egg whites and mayonnaise or sour
cream; stir gently to blend. Spray a shallow baking pan with non-stick
Place a heaping teaspoonful of stuffing in
each mushroom cap and arrange mushrooms in baking pan. Bake at 400 degrees F for 20 minutes or
until lightly browned on top.
Transfer mushrooms to a serving platter,
garnish with lemon wedges and serve hot.