Brown the sausage in a skillet, stirring until crumbly, drain.
Combine the eggs and milk in a bowl and beat well. Stir in the cheddar cheese, salt, dry mustard, and sausage.
Cut the bread slices into cubes. Sprinkle into a greased 9x13" baking dish. Pour the egg mixture over the bread cubes. Chill, covered, in the fridge for 8-10 hrs.
Bake, uncovered, for 45 minutes at 350 degrees.
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