Preheat oven to 375ºF. Drizzle garlic with EVOO, season with salt and pepper, and wrap tightly in a foil pouch. Roast until light golden and just tender. Let cool to handle then press cloves into a bowl and mash with a knife.
Heat vermouth and stock; whisk in roast garlic paste and herbs. Finish the sauce with butter and lemon juice. (As a variation, you can finish the sauce with Dijon mustard and tarragon!)
Drizzle chicken with EVOO and season with salt and pepper. Roast chicken 15 minutes, pour sauce over and roast for 20 minutes more. Serve with crusty bread alongside.