Preheat oven to 350 degrees F (180C). Spray an 8-inch square baking dish with cooking spray.
Place sauerkraut in the bottom of the prepared dish. Top with tomato slices and drizzle with salad dressing. Add diced corned beef over top, and sprinkle with grated cheese.
Bake, uncovered, for 20-25 minutes, or until heated through. Garnish with fresh parsley, if desired.
