Sourdough Egg Cheddar Breakfast Casserole

1 pound sourdough
4 tablespoons melted butter
12 ounces bacon
1 large onion, sliced
28 ounces diced tomatoes, drained 
4 cups cheddar cheese 
4 green onions, chopped
1 3/4 cups chicken stock
Salt
6 eggs

While preheating oven to 350 degrees, in a large mixing bowl toss the sourdough and butter. Spread the sourdough evenly on a large baking sheet and bake for 20-25 minutes or until bread is golden brown.
In a large skillet over medium-high heat, cook the bacon until crisp. Once the bacon is cooked, transfer it to a paper towel lined plate. Save 2 tablespoons of the bacon grease, pouring out the rest.
Add the onion to the skillet and cook until caramelized (approximately 10 minutes).
Now add the tomato and cook until all the liquid has evaporated (approximately 5 minutes). 
In a large mixing bowl, pour the onion mixture and add the bread, bacon, green onion, stock and cheese. Stir together until well mixed and season to taste with salt.
Spread this mixture into a 9x13 inch baking dish and cover with tin foil, and refrigerate overnight.
To bake:  Preheat oven to 350 degrees.  Keep the tin foil on the baking dish and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes.
Now, remove from oven and make 6 indentations in the bread. Once the indentations have been made, crack 1 egg into each indentation. Once all 6 eggs have been added to the indentations, bake for another 15 minutes or until egg whites are set.