Preheat oven to 350 degrees F.
Begin by preparing shanks: On a large plate, season flour with plenty of salt and pepper then lightly dredge the shank pieces. Set a large, heavy-based pot or Dutch oven over medium-high heat. Add a 2-count of olive oil then carefully add the shanks to the pot and brown all over. Remove the shanks to a plate and set aside. Toss in the garlic, carrots, onion, bay leaf, thyme and cloves. Cook for 2 to 3 minutes, browning the vegetables, then add wine, beef stock and finally barley. Return the shanks to the pan. Cover and roast in the oven for 2 hours.
While they are cooking, prepare the potato crust and Garlic-Parsley Butter: Chop garlic, drizzle with olive oil and sprinkle with salt. Press and mash the garlic with the flat blade of your knife to form a paste. Fold in the chopped parsley. Melt the butter in a small sauce pot and add the garlic-parsley mixture. Cook over low heat for 5 minutes and set aside. Peel the potatoes and cut in half lengthwise.
After the stew has been cooking for 2 hours, remove from oven and arrange potatoes on top to completely cover the stew - you may have to cut some of the potato pieces smaller to fit. Place back in the oven uncovered and bake for 30 to 45 minutes or until the potatoes are cooked, then baste with garlic-parsley butter.
Serve the stew garnished with parsley sprigs.