Place roast on a large plate and sprinkle with 3 tablespoons of pot roast seasoning on all sides, pressing it into the meat and using up all the seasoning from the bottom of the plate.
Preheat large non-stick skillet on medium heat and add olive oil. Sear roast for 45 seconds per side or until just golden crust forms.
At the bottom of large slow cooker, spread onion, carrots, celery and add roast on top. Spread baby potatoes and bay leaves around it and pour beef broth, apple cider vinegar and Worcestershire sauce on top of them. Then sprinkle potatoes with remaining 1 tablespoon seasoning and top with cubes of butter.
Close the lid and cook on Low for 10 hours or until meat is tender and easily pulls apart with a fork or on high heat for 5 hours.
After shred meat with two forks right in the slow cooker or slice on a cutting board. Stir and serve with the vegetables and au jus.
Notes
Store: Let the cooked dish cool down to room temperature, then transfer to an airtight container and refrigerate for up to 3-4 days.Freeze: I do not like the texture of potatoes once thawed. However, I know many people are OK with freezing cooked potatoes. Freeze roast in an airtight container with some room for expansion for up to 3 months. Then defrost in the fridge overnight.