1. Using a sharp knife, cut a 1/2" crosshatch pattern about 1/4" deep into fat cap and meat; transfer to a roasting pan. Mince four garlic cloves and place in a small bowl. Add 2 tablespoons oil, rosemary, chopped thyme, lemon zest, 1 tablespoon salt, and 2 teaspoons pepper, and stir to combine. Rub mixture all over lamb and let sit at room temperature for 30 minutes to 1 hour.
2. Center a rack in the oven and heat to 450 degrees. Toss together potatoes, remaining three garlic cloves, thyme sprigs, and remaining 3 tablespoons oil in a large bowl and season with salt and pepper. Arrange potatoes around lamb, transfer to oven, and roast until top of lamb is beginning to brown, about 20 minutes.
3. Reduce oven temperature to 350 degrees and continue to roast until center of lamb registers 130 degrees, about 1 1/2 hours, stirring and basting potatoes a few times throughout cooking. Remove lamb and potatoes from oven, cover loosely with foil, and let rest for 20 minutes before serving.
Source: Hannaford fresh Magazine, March - April 2018