Tomatoes, rather than cream or stock, provide the moisture in this gratin. Dried rosemary and thyme not only perfume the potatoes, but taste delicious with the lamb. If you like, use rib instead of loin chops.
Bordeaux is the classic choice with lamb chops. Though our perceptions of Bordeaux are often distorted by the wildly expensive cru classé wines, many wines from the region are both affordable and delicious. Look for the appellations Bordeaux Supérieur, Bourg, Blaye, and Fronsac.