Heat large pot or dutch oven over medium high heat. Add oil and let it get really hot. Salt and pepper the chuck roast on both sides. Cut onions in quarters. Brown onions on both sides in dutch oven, then remove to a plate. Thoroughly wash carrots, chop and add to dutch oven and toss them around until slightly brown, about a minute or so. Remove the carrots and allow pot to become hot again. Sear roast about 1 minute per side and then move to oiled crockpot. Turn heat to high on pan and deglaze the pot adding one cup of the beef broth. Pour deglazing liquid over pot roast followed by onions and corrots. Then add enough broth to cover the meat half way. Sprinkle on Thyme and Rosemary. Cover and cook on high for 4-5 hours depending on size of roast. Check frequently with a fork until desired tenderness.