Reserve 2 tablespoons each onions and tomatoes. Cook bacon in large skillet until crisp. Remove bacon with slotted spoon to paper towels; reserve 1 tablespoon drippings in skillet. Add mushrooms to skillet; cook and stir 2 minutes or until tender. Remove
from heat. Chop bacon. Add to skillet with onions and tomatoes; mix well.
Beat eggs and sour cream with whisk until well blended. Pour into greased 13x9-inch baking dish; top with bacon mixture and cheeses.
Bake 30 minutes or until center is set. Sprinkle with reserved onions and tomatoes. Let stand 5 minutes before cutting to serve.