Cook sausage in a skillet over medium heat until browned. Drain excess fat.
In a bowl, mix together mustard powder, salt, beaten eggs and milk.
Toast your six slices of bread and cut them into small cubes. Add sausage, bread cubes and cheese to egg mixture and stir to coat evenly.
Pour into a greased 9x13 inch baking dish. Cover dish and place in the refrigerator for 8 hours or overnight.
In the morning, preheat oven to 350 degrees. Cover and bake for 45-60 minutes. Uncover, reduce temperature to 325 and bake for an additional 25-30 minutes or until just set.