Arrange half of bread slices on work surface.

Sprinkle with half each of cheese and onions; sprinkle with bacon.

Top with remaining bread slices.

Cut each sandwich in half, crosswise. Arrange sandwich halves, overlapping, alternating with tomato slices, in greased 13x9 inch baking dish.

Beat eggs, mustard and Worcestershire sauce with wire whisk until well blended; pour over ingredients in baking dish.

Cover and refrigerate at least 6 hours or up to 24 hours.

Preheat oven to 350°F. Remove cover from baking dish; sprinkle casserole with remaining 3/4 cup cheese and remaining green onions.

Bake 50 minutes to 1 hour or until center is set. Remove from oven. Let stand 10 minutes before cutting into pieces to serve.