Preheat broiler with oven rack 6 inches from heat. Prepare gravy according to package directions, substituting 1 cup milk for water. Remove from heat. Whisk in 1/2 cup Parmesan cheese; season with salt and pepper to taste. (Sauce will be thick.)
Arrange bread slices in a parchment paper-lined 15- x 10-inch jelly-roll pan. Top with turkey and sauce; sprinkle with remaining 1 cup Parmesan cheese.
Broil 5 to 6 minutes or until cheese is melted and lightly browned.
Meanwhile, microwave bacon according to package directions until crisp; crumble. Top each sandwich with crumbled bacon and tomato slices. Garnish, if desired. Serve immediately.