Season roast with salt and pepper. Keep aside.
Heat butter and oil in a large nonstick pot or pan and sear all the sides until golden brown.
Transfer meat to your slow cooker.
In the same pot or pan you browned the meat, add onions, garlic and saute for a few minutes until garlic is fragrant.
Add beer and deglaze the pan, scraping all the brown bits from the bottom of the pot.
Transfer this onion mixture and all the juices to the slow cooker.
Add broth, Worcestershire sauce, thyme, additional salt and pepper (if necessary). Mix.
Cover and cook on High heat for 3-4 hours or on Low heat for 5-6 hours or until meat is very tender.
Transfer meat to a serving dish and shred it with 2 forks.
Discard the bay leaf.
Strain liquid remaining in crockpot through a fine mesh strainer into a bowl and serve this strained Au jus with sandwiches for dipping. On busy days, I just skip this straining step and shred the meat in the crockpot and it still tastes really good.
Transfer the shredded meat and the onions back into the slow cooker. Pour over a little bit of au jus to moisten the meat.
Pile meat onto toasted buttered rolls.
Top with cheese. Heat in oven on broiler setting until cheese starts melting. I also added some sliced jalapenos because I really like them.
Enjoy with the strained Au jus. If there is not enough Au jus for everyone, mix in a a little more broth to the Au jus.