Decide what filling option you would like to use.
Option 1- Bacon, cheddar, mushroom and tomato: Sprinkle 2 cups grated cheddar cheese over the bread cubes. Distribute 1 cup crumbled cooked bacon (6-8 strips), 1 cup sautéed sliced white or shitake mushrooms, and 1 cup chopped tomatoes over the egg mixture.
Option 2- Chicken, broccoli, corn, chilies, and jack: Sprinkle 2 cups Monterey Jack cheese over the bread cubes. Distribute 1 cup frozen corn kernels, 1 cup cooked broccoli florets, (2) 4.5 ounce cans (drained) chopped green chilies, and ½ cup shredded cooked chicken over the egg mixture.
Option 3- Ham, Swiss and Asparagus: Sprinkle 2 cups grated Swiss cheese over the bread cubes. Distribute 1 cup blanched asparagus pieces, 1 cup cubed ham and ½ cup caramelized onions over the egg mixture.
Option 4- Fontana, Spinach, Salami and Roasted Garlic: Sprinkle 2 cups Fontana cheese over the bread cubes. Distribute 1 cup frozen chopped spinach, 1 cup Italian salami (cut into match sticks) and ½ cup roughly chopped roasted garlic cloves (see below) over the egg mixture.
Option 5- Vegetable-Blue Cheese: Sprinkle 1 cup crumbled blue cheese over the bread cubes. Distribute 1 cup cooked cubed celery root, 1 cup sautéed sliced zucchini and ½ cup sautéed sliced onions over the egg mixture.
Butter a 9 x 13 inch baking dish. Put the bread cubes in the dish and sprinkle them with the cheese. In a large bowl, whisk together eggs, milk, mustard and salt. Pour the egg mixture over the bread cubes. Sprinkle the filling ingredients over the egg mixture and fold them gently. Cover and chill for at LEAST 4 HOURS AND UP TO 24 HOURS.
Heat the oven to 350 degrees.
Uncover the baking dish and bake for 60 minutes, until the mixture has puffed up slightly and is golden brown on top, and the strata doesn’t shimmy with uncooked custard when you shake the pan. Tent the dish with foil if the top is browning too quickly. Let cool for 5 minutes before serving. Serve by the spoonful, using a large serving spoon.