Heat a large skillet, over medium heat, and add oil and butter.
Add the onion and carrot halves and cook until the vegetables are seared (browned). Turn the vegetables over and sear the other side.
Transfer the vegetables to the slow-cooker.
Generously sprinkle the entire roast with salt, pepper and smoky paprika. Set the roast in the skillet, press down and brown the meat for 4-6 minutes (or until beautifully seared) on the bottom side. Turn the roast over and brown it on the other side. When the roast has browned, set it on top of the vegetables in the slow-cooker.
Reduce the slow-cooker temperature to LOW.
Add 1-cup beef broth, wine, Worcestershire Sauce, bay leaf, rosemary, and thyme.
Cover and cook 4 hours.
Add the additional root vegetables over the roast, if using. Cover and cook an additional 3-4 hours or until roast and vegetables are fork-tender.
Remove the vegetables from the top of the roast and, then, remove the roast. Keep the food warm in a covered dish set in a warm oven.
To make the gravy, use a hand-blender (immersion blender) to puree the remaining vegetables and beef juices. (Alternatively, a stand blender can be used to puree the gravy. Take extra care with the hot ingredients, though.)
To serve, separate the beef into large chunks. If a deep platter is available, pour some of the gravy onto the platter and place the beef chunks and cooked vegetables over it.
Garnish with chopped fresh parsley and serve with remaining gravy.