Heat oil in skillet or Dutch oven . Blot roast dry with paper towels. Sprinkle all sides with salt and pepper.
Sear roast on all sides until brown.
Place onion slices and celery in the bottom of crockpot. Add seared roast on top.
In a small jar with lid, add the Better than Bouillion, garlic and hot water. Close the lid and shake vigorously to combine. Pour over the roast.
Sprinkle the Ranch dressing mix over the roast. Add thyme, Add banana pepper slices on top of the roast and top with butter. Cover and cook on low for 8 hours.
About 5 hours into cooking, add the potatoes and carrots around the pot roast, then mushrooms on the top. (Add what you can fit around the pot roast but you can add the ones that do not fit around it to the top.)
Continue cooking for 3 more hours, or until potatoes are tender.
Serve hot with crockpot drippings.
