Cut bread in half horizontally; hollow out top and bottom, leaving a 3/4-in.shell.
Save removed bread for another use.
In a large skillet, cook sausage, onion, green pepper and mushrooms until sausage is no longer pink and vegetables are tender.
Remove mixture and set aside; drain all but 1 tablespoon of drippings.
Add eggs; cook and stir gently until set.
Stir in sausage mixture; remove from the heat.
Place bread bottom on a large sheet of foil.
Combine cheeses; sprinkle half in the bread bottom.
Spoon in the egg mixture and cover with remaining cheese.
Replace the bread top and wrap tightly with foil.
Bake at 400° for 25 minutes or until the filling is heated through.