Cut the sausage links into pieces and cook until brown. Drain on paper towels
and set aside.
Combine the eggs, 2-1/2 cups milk and mustard.
In a 9x13/2 baking pan, layer the croutons, cheese and sausage and pour the
egg mixture over the top.
Cover and chill several hours or overnight.
When ready to bake, combine the soup and 3/4 cup milk. Stir well and spread
over the top of the casserole.
Bake in a 325 degree oven about an hour and 15 minutes, or until a knife inserted
in the middle comes out clean. It should be slightly brown when done.