1 large sweet onion thinly sliced
6 strips thick-cut bacon
3 cups fresh spinach roughly chopped
5 eggs
1 cup milk
1/2 teaspoon fresh thyme (dried works too)
1/4 teaspoon salt
1/4 teaspoon pepper
3 cups ciabatta or other dense bread cut into 1/2 inch cubes
4 ounces shredded Swiss cheese
In a large skillet cook the bacon removing each piece when crisp. Once cooled, chop and spread across the bottom of a 2-quart baking dish.
Using 2 tablespoons of the bacon drippings, in the same skillet, quickly sauté the spinach just until is wilted; spoon spinach over bacon in the baking dish. Using the remaining bacon drippings add the rings of sweet onion to the skillet and slowly cook over medium heat, removing them as soon as they turn a rich caramel brown color. Set aside.
In a medium bowl hand-whip the eggs, milk, thyme, salt and pepper until well combined; stir in the cheese. Pour mixture into baking dish on top of the bacon and spinach. Distribute the bread cubes across the dish pushing them into the mixture and then spread the caramelized onions across the top of the dish.
Bake at 350°F for about 40 minutes; until set and lightly browned on top. Let stand 10 minutes before serving.