Mix And Match Breakfast Casserole

2 cups milk
6 eggs
6 slices of bread, cubed
1 onion, diced
1/4 teaspoon mustard, ground
2 cups your choice shredded cheese (Cheddar, Swiss, Mozzarella, etc.)
1/2 cup your choice meat (sausage, bacon, ham, etc)
1/2 cup your choice vegetables (tomato, spinach, etc)

Preheat oven to 350 degrees, and spray a 9x13 inch casserole dish with cooking spray.
In a large mixing bowl, add all ingredients and mix together. Once mixed, pour into the greased baking dish and bake for 60 minutes.
Remove and let stand for 5 to 10 minutes before serving.
Will serve 3 to 4.