Preheat your oven to 275F and move the rack to the middle position.
Season your roast with salt & pepper. Add 2 tablespoons of olive oil to your Dutch oven over medium-high heat and sear the roast on all sides until browned. Transfer the roast to a plate.
Add another tablespoon of olive oil to the Dutch oven if it's looking a bit dry, and then add the onions. Turn down the heat so they don't burn (the pot will be very hot), and sauté for 5-7 minutes or until softened and lightly browned.
Stir in the garlic and cook for 30 seconds, then add in the wine, broth, Worcestershire sauce, and Italian seasoning. Scrape up any browned bits from the bottom of the pot.
Once it starts to simmer, add the roast back in and turn off the heat. Place the carrots and potatoes around the roast, then add the rosemary on top. Cover and roast for 3-4 hours (I do 3.5 hours for a 3 lb. roast) or until the meat is fall apart tender. Note: If you prefer firmer vegetables, add them in an hour later (you may need to experiment for exact timing depending on how big everything is cut etc.).
Remove the rosemary sprigs, then skim some of the fat off the surface (I just use a spoon) and discard it. Don't worry about getting all the fat!
Take the meat, potatoes, and carrots out of the pot (you may want to use a large bowl or a couple of plates). In a small bowl, make a cornstarch slurry by adding 3 tablespoons of cold water to the cornstarch and mixing it together. Pour it into the pot and then simmer over medium-high heat until the sauce thickens a bit (add more cornstarch if you want a super thick gravy). Give it a taste and add more salt & pepper as needed (I am generous with both).
Add the beef back in and shred it with two forks, then add the carrots and potatoes back in and toss with the gravy. Enjoy!