You must prepare this recipe before going to bed the day before you plan to eat it. Crack eggs into a large bowl and lightly beat. Add one cup of milk and ground mustard. Mix well. Add cheddar cheese, sausage and mushrooms to bowl. Tear bread into pieces (crust and all) and place into the bowl. Stir until all is incorporated. Pour into a 9×13″ Pyrex pan sprayed liberally with Pam cooking spray. Cover with Saran wrap and refrigerate overnight.

The next morning, remove pan from refrigerator and preheat oven to 325 degrees. Bake for 45 minutes to 1 hour (or until eggs are set in the middle).