Pierre Marcolini is all seriousness. Belly up to the sleek wooden bar of this Belgian chocolatier for a selection of palet fins or pralines, chocolates filled with flavored ganache, caramel, or nuts. Mr. Marcolini proves it's all in the bean with his specialty saveurs du monde chocolates, which are made with a single kind of cacao from a single location such as Madagascar, Venezuela, or Ecuador. Métro: Mabillon.