1In a slow cooker, add one medium onion (roughly chopped), eleven cloves of garlic, four sprigs of rosemary, one cup of red wine, two cups of beef stock, two tablespoons of Worcestershire sauce, and two tablespoons of soy sauce.
2Get a three to four pound chuck roast, pat it dry with a paper towel, season it with salt, and brown it in a pan on medium heat.
3Add the roast to the slow cooker and season generously on both sides with beef bouillon powder, salt, and pepper, and granulated garlic.
4Cook on low for eight hours.
5While the beef cooks, make caramelized onions by adding five tablespoons of butter to a pan on medium-low heat along with five medium onions cut into half moons.
6Cook for about one hour, stirring frequently and season with salt and pepper.
7Once the beef is done, separate it from the liquid, shred it in a bowl, and stir in the caramelized onions.
8Strain the juice from the slow cooker and set aside; this is the au jus.
9In a bowl, make a spread by combining half a cup of mayo, three tablespoons of cream style horseradish, salt and pepper to taste.
10Get a large French baguette, cut it in half, add the spread, beef, and top with Swiss cheese.
11Close the baguette, cover it tightly with foil, and bake in the oven at 325 degrees for ten to fifteen minutes, or until the cheese melts.
12Cut into small sandwiches and serve with au jus.