Preheat oven to 350°F. Season chuck roast with salt, Montreal seasoning and black pepper.
Heat oil in a Dutch oven or oven-safe pan. Sear roast for about 5 minutes per side, then remove and set aside.
Add butter and onion to the same pan and cook for 5 minutes. Add garlic and cook for 30 seconds. Season with brown sugar, salt and black pepper.
Add tomato paste and cook for 2 minutes. Stir in flour and cook for another 2 minutes. Slowly pour in beef broth while stirring. Bring to a simmer and season to taste.
Add half the carrots to the bottom, then return the roast to the pan. Arrange the remaining carrots and baby potatoes around the roast. Add oregano, rosemary, thyme and bay leaves.
Cover and bake for 3 hours, or until the beef is fall-apart tender. Remove the herb sprigs and bay leaves before serving.
