Witness the alchemy firsthand: Confections at Serenade, Brookline Village’s intimate chocolatier, are prepared before customers’ eyes using smooth, buttery Callebaut direct from Belgium. It’s a show that has lured in locals, siren-like, for some 15 years now. Then there’s the serenade itself: the chocolate. The truffles are an adagio in their own right, each subtly laced with flavor (Champagne, Grand Marnier, raspberry) that plays to a smooth, dense ganache core encased in a layer of chocolate. The French truffle dusted in bittersweet cocoa is a standout, but the house signature is the Viennese, a fat square of layered dark and milk chocolate infused with hazelnut butter. Serenade also runs a small stand in South Station, lulling the train-bound and softening the commute home.