Combine the onions, garlic cloves, carrots, rosemary, thyme, bay leaves and parsley in the bowl of the slow cooker.
Season the beef roast with salt and pepper, and rub with the dried basil. Heat the olive oil over a medium-high heat in a frypan and when hot place the beef in. Sear on all sides until the roast is browned and add to the slow cooker, ensuring it is nestled in amongst the other ingredients.
Pour the beef stock and red wine over the pot roast and stir to combine with other ingredients.
Cook on low for 6-8 hours and remove from the slow cooker to rest for 10 minutes before slicing.
Meanwhile, pour the juices from the slow cooker into a fry pan and cook on medium until reduced and thickened, about 10 minutes.
Serve with potatoes, salad or steamed vegetables, pouring the juices from the slow cooker over the meat.