Assemble this dish the night before and bake off in the morning. Serve with bagels, toast or even mini-croissants, if you have an older crowd.
In a medium skillet coated with Teflon® non-stick, cook the bacon over medium heat until tender; remove to paper towels to drain and then coarsely chop; set aside. Pour out all but 1 tablespoon of the bacon renderings and return the pan to stovetop. Sauté the onions and add the mushrooms, cooking a few minutes until the mushrooms are soft.
Preheat the oven to 375 degrees. In a mixing bowl, beat the eggs and then beat again with the milk; add the mustard, tomatoes, basil, oregano, cheeses, chopped bacon, and the mushroom onion mixture.
Transfer to a 10-inch pie plate coated with Teflon® non-stick and bake in the oven 40 to 45 minutes or until the top is set and a warm golden color. Let stand for 6 minutes and slice into pie-shaped wedges and serve garnished with sprigs of chives.