Using the tip of a sharp paring knife, make 20 evenly spaced small slits, about 1 ½ inches deep, all over the pot roast. Using your fingers, insert the garlic cloves as deep into the meat as possible. Season the roast on all sides with the salt and pepper.
Wash hands well before continuing.
Heat a Dutch oven or heavy, tall pot with lid over high heat. Add the oil and, when hot, use a meat fork to add the roast. Sear the meat on all sides until very well browned, about 4 to 6 minutes per side.
When the roast is evenly browned on all sides, carefully add the stock and cover the pot.
Reduce the heat to low/medium-low and cook the roast until it is very tender, about 3 to 3 ½ hours, turning 2 or 3 times while cooking.
Check occasionally to make sure that there is always a little liquid on the bottom of the pan. Add more stock if necessary.
When the roast is very tender, carefully transfer to a serving platter with a meat fork. Slice or pull meat apart into serving pieces and serve with the pan juices drizzled over the top.