Preheat your oven to 350 degrees F.
In a food processor or blender, combine the cream cheese, sour cream, mayo, ketchup, relish, and horseradish mustard. Puree until smooth.
To a large bowl, add the sauce, swiss cheese, gruyere cheese, corned beef, sauerkraut, and fresh parsley. Stir to combine thoroughly.
Pour the mixture into a small baking dish. Bake at 350 degrees F for 15-20 minutes or until bubbly.
Serve immediately with dark rye toasts. Enjoy!