Preheat sous vide cooker to 134°F.

Using a small bowl, combine all ingredients except for beef, thyme and rosemary. Rub mixture evenly over beef.

Place beef, thyme and rosemary in Foodsaver® Sous-vide Vacuum Seal Bag. Seal bag and place in water bath. (Note: Sealed bags can also be refrigerated or frozen at this step for later use.) Ensure that the bag is entirely submerged under water.

Cook for 6-8 hours. (Note: If needed, add more water to make sure bag stays entirely submerged throughout cooking time.)

Preheat cast iron skillet over high heat. Remove roast from bag and sear in hot skillet for 45-60 seconds per side.

Allow roast to rest for 10 minutes before slicing against the grain into very thin slices.

Using a small bowl, whisk all ingredients together until well combined.

Preheat large griddle or cast-iron skillet over medium heat.

Butter the inside of the rolls and then sprinkle Italian seasonings and garlic powder on top. Add horseradish mayo, sliced beef and grated cheeses on top.

Place sandwiches onto griddle and tent with a piece of foil. (The foil helps ensure that the cheese on top melts.)

Cook for 6-8 minutes, or until cheese has completely melted.

{Optional} Garnish sandwiches with minced parsley before serving.