24 to 36 hours before you intend to start roasting the pork, combine the garlic, rosemary, thyme, salt, and pepper. Use a sharp knife to poke deep holes into the roast and stuff them with about half the herb mixture. Rub the roast all over with the remaining herb mixture, cover, and refrigerate.

To roast, preheat oven to 250ºF.

Line a roasting pan with foil, place a rack in the pan, and lay a sheet of parchment paper on the rack. Transfer the pork to the pan and drizzle with olive oil. Transfer to the oven and roast until a fork inserted in the thickest portion meets little resistance when twisted, 6 to 8 hours.

Remove from the oven and tent with foil; let rest for 20 minutes.

While the pork rests, increase the oven heat to 500ºF. Return the roast to the oven and cook, rotating the pan every 5 minutes, until browned to your liking, 12 to 20 minutes.