Not much to it really. Ask your meat cutter to french the two racks of lamb
and tie them for you. I like to season with s & p, garlic powder, Drizzle olive oil on and rub it in, with rosemary, thyme. Place on rack on half sheet pan and roast 450° for 15 to 20 min, until internal temp is around 130 to 135. Remove from oven and let sit about 15 minutes before carving. I like to serve with roasted garlic mash potatoes, and either grilled or roasted fresh asparagus.
Notes: I have fresh rosemary and thyme in my garden, so I use that. Sometimes I like to stuff fresh garlic slices into the slits the meat cutter makes in the two racks so he can curve the meat into a circle.
Frankly, I think the individual racks of lamb are easier to work with, and taste just as good. But if a WOW presentation is what you are after, this is the way to go. Have fun!
Mint is also nice with lamb. I love that Cross and Blackwell minted lamb sauce and have used that sometimes and rubbed well into the racks. It is also great for a dipping sauce for the chops.