How to Make It
Put the prime rib roast on a large rimmed baking sheet and generously season all over with salt. Refrigerate uncovered overnight. Let the roast stand at room temperature for 2 hours before cooking.
Preheat the oven to 475°. Set a rack in a large roasting pan and lay the rosemary sprigs across the rack. Season the roast all over with salt and set it on the rosemary, fat side up. Roast for 30 minutes, until browned. Reduce the oven temperature to 275° and roast for 40 minutes longer, until an instant-read thermometer inserted in the center registers about 65°. Remove from the oven and let stand for 30 minutes. Return the roast to the oven and roast until an instant-read thermometer inserted in the center registers 125°, 40 minutes to 1 hour. Remove from the oven and let rest for 30 minutes.
Meanwhile, in a large saucepan, combine the cherries with the sugar and a pinch of salt and cook over moderately high heat, stirring occasionally, until the cherries start to break down and are coated in syrup, about 15 minutes. Season with salt and pepper. Keep warm over very low heat.
Transfer the roast to a very large carving board. Carve between the bones. Spread the steaks with some softened butter and top with the warm cherry conserva, finely grated chocolate and shaved truffle. Serve.
The 50-day dry-aged rib roast is available at select butcher shops and from lafrieda.com.