Season the chuck roast on all sides with salt, pepper, and garlic.
Melt butter in a skillet over medium high heat and sear chuck roast on all sides.
Put the seared chuck roast in a crock pot.
Add sliced onions, minced garlic, Worcestershire sauce, beer, and brown gravy mix to the hot skillet stirring and letting it simmer.
Pour the onion and gravy mixture over chuck roast in the crock pot and let cook on low for 6-8 hours.
Build sandwiches and pop in the oven for just a few minutes to melt the cheese.
