Perhaps this is something that's been made before... but I put a couple of twists on it to make it even better, and baked one up on Superbowl Sunday 2011.
Enjoy this egg bake warm out of the oven, or the next day.
If you're not someone who likes to mess around in the kitchen on mornings, make it ahead of time and cut the dish up into serving size pieces, and place into plastic bags or tight-sealing containers to freeze.
When you want a hot breakfast fast, place a piece on a microwave safe plate and zap in the micro for a few minutes!
TIPS: I used smoked, cooked bacon bits in a pouch for this recipe, but you can chop and fry regular bacon, too. Be sure to cook it very well until crisp, otherwise it may come out rubbery in the dish. Also, cool it completely and drain off all the fat, onto paper towels/kitchen paper.
Preheat oven to 400 F. Spray a baking pan (I use glass) with cooking spray.
In a mixing bowl, whisk together eggs, milk, sour cream, dash of salt & pepper, and hot pepper sauce to taste (I let the sour cream sit on counter until softened OR blend in food processor with milk and eggs). Set aside.
Shred cheeses. Combine cheese shreds into one bowl with your hands and then set aside.
Dice and seed tomatoes (important! the egg bake will be runny if you do not seed tomatoes). Set the tomatoes aside. TIP: if your tomato pieces seem very watery, sprinkle a bit of salt on them to draw out excess liquid (be sure to drain this off before adding to dish)
Slice about 5 to 6 thin rings off the onion while it's still whole, and set aside, then dice the remainder of the onion.
Spray a small skillet with cooking spray and turn on heat. Put the diced onions into the pan and sweat them (cook until transparent and a moist). Take onions off the heat.
In your baking dish, place the bread on the bottom, cutting pieces if necessary, to fit. Sprinkle the bacon bits, tomatoes, diced onion and 1/2 the combined cheese shreds over the bread.
Pour the egg mixture over all, and top with the sliced rings of onion in a decorative fashion.
Spray a sheet of aluminum foil large enough to tightly cover dish with a bit of cooking spray (as egg bake will rise and otherwise stick to foil), cover dish tightly with it, and bake for 40-45 mins at 400 F.
When the timer goes off, remove dish from the oven, and remove foil. The egg bake might still be pretty wet in a small part of the center, and jiggle a bit. This is O.K. Don't attempt to "test" the dish with a toothpick or knife at this point. If you'd like to add some fresh herbs like basil or thyme, you can do so now. Sprinkle the remaining shredded cheese mixture over the top (over herbs, if added), place back into the oven and bake for 10 more minutes, or until cheese is golden and bubbly. The egg bake should tighten up more and stop being "jiggly" at this point. Let sit for about 5-8 minutes before cutting and serving. Enjoy!