Place rack into the middle position, and then preheat oven to 350f (175c).
Lightly grease a 9-inch pie pan, and set aside.
Dice the bacon, and fry up in a large skillet, at medium-high heat, until nice and crisp.
Remove the bacon from the pan, and allow to drain on paper towels. Set aside.
Meanwhile, remove all but 2 tablespoons of the bacon fat from the pan, and return to the stovetop.
Add chopped onions and cook, stirring occasionally, until onions are soft, about 4 to 6 minutes.
Stir in spinach, reduce heat to medium, and continue cooking until excess moisture has evaporated.
Chef’s Note: You don’t want the mixture to dry out… just evaporate off the puddles of liquid.
Remove the pan from the heat, and allow to cool slightly.
In a large bowl, beat the eggs, then add the cheese, salt and pepper, and combine. Then add the spinach/onion mixture, and the reserved bacon.
Blend together until evenly mixed.
Chef’s Note: Avoid, at all costs, the pre-shredded cheeses that are out there. In order to keep the cheese from clumping, they toss the cheese with things like powdered wood pulp… And if you have any problems with that, don’t worry because the USDA says that wood pulp is completely safe for consumption ;-)
Chef's Note: I have always maintained that Feta cheese is an acquired taste… But its use in this dish really kicks up the flavor. So, if you've avoided Feta, I would really recommend you give it a try in this dish.
Place mixed ingredients into the prepared pie pan, and then add the tomatoes to the top, and slightly press them into the mixture.
Bake in preheated oven until eggs have set, about 30 minutes. Let cool for 10 minutes before serving.
Cooking Tip: If you have a good cast-iron pan, you could cook the bacon, onions, and spinach, and then add the eggs and cheese, and put the pan into the oven. Making this a rustic, one-pan dish.
Presentation Tip: If you have a baking pan that does mini quiches… these make a brilliant appetizer for your guests at your next dinner party.