One day it's an item you're reading about in Fergus Henderson's masterpiece about eating nose-to-tail "The Whole Beast" and then suddenly it's everywhere. No, we're not talking about chef Henderson's recipe for jugged hare; we're talking about roasted marrow bones. It is truly one of the most decadent dishes you can eat and also the most simple. Marrow bones are split, roasted, and then served with lightly dressed parsley to be piled up on slices of toast. The roasted marrow is gelatinous and unctuous, being mostly fat, but it is rich and delicious. Wit and Wisdom and Corner BYOB are among the local restaurants that have it on their menus, but if you've never had it, start with Le Garage's version; it's the best in town.