1Spray a 13x9-inch (3-quart) glass baking dish with the cooking spray. Peel and thinly slice the green onions; you will need about 1/2 cup. Trim crusts from the bread.
2Arrange 6 bread slices in baking dish. Layer the ham, cheese and onions on bread in dish. Cut remaining bread slices diagonally in half; arrange on onions.
3In a medium bowl, beat the eggs, milk, mustard and pepper sauce with a fork or wire whisk; pour evenly over bread. Cover with plastic wrap or foil and refrigerate up to 24 hours.
4Heat the oven to 300°F. Uncover strata and sprinkle with paprika. Bake uncovered 1 hour to 1 hour 10 minutes or until center is set and bread is golden brown. Let stand 10 minutes before cutting into serving pieces.