2In a skillet over medium heat add butter, melt. Add mushrooms, cook until tender, then drain. In the same skillet add sausage, cook until browned; drain.
3Line the bottom of the baking dish with bread, cutting to fit where necessary. If there is bread left over, cube it and spread evenly over the other bread. Sprinkle layers of cheese, mushrooms and sausage over the bread layer.
4Beat eggs in a bowl. Add milk, salt, paprika and dry mustard. Pour egg mixture over the top of the casserole. Cover dish with foil; bake 25 minutes, or when eggs are not runny.