Coat shallow 2-quart baking dish with cooking spray. Arrange half the bread in single layer in dish, cutting to fit. Cover with half the scallions, bacon, cheese and tomatoes. Repeat for a second layer.
Combine eggs, milk, pepper and hot-pepper sauce. Pour over casserole; cover. Can be made ahead and refrigerated for up to 2 hours.
Heat oven to 375 degrees F. Bake, uncovered, at 375 degrees F for 45 minutes or until lightly browned. If browning too quickly, cover loosely with foil.