1. Cut the bread into 1-inch cubes and spread in the bottom of a greased 9- by 13- by 2- inch casserole dish.
2. In a medium skillet, brown the sausage over medium heat until fully cooked and no longer pink. Remove the sausage with a slotted spoon to drain the fat. Spread the cooked sausage over the bread and top with the cheese.
3. Then stir together the, half-and-half, dry mustard, salt and eggs. Pour this mixture over the cheese. Cover the casserole with alluminum foil and refrigerate for 8 hours or overnight.
4. The next day, preheat the oven to 180°C.
5. Bake the covered casserole until set and slightly golden, about 50 minutes. Remove from the oven and allow the casserole to set for 15 minutes before serving.