Christine Ferber is one of France's most talented pastry chefs and in fact was voted pastry chef of the year for 1998. Childhood friend of Pierre Hermé, Ferber also grew up in Alsace, a place where baking is taken very seriously, and like her friend, has written prolifically on the subject. I have four of her books, one on jams and preserves, one on pickling and pates, another on cooking with fruit, and the one from which I very loosely adapted this recipe, Mes Tartes Sucrees et Salees (My Tarts, Sweet and Savory).
In fact, my recipe is a combination of several of Ferber's. The tart is a baked ganache (a simple mixture of chocolate and cream), scented with orange zest and rum, topped with chopped walnuts, in a sweet walnut pastry crust. A final drizzle of chocolate makes a simple decoration. Although it wouldn't be very French, I think pecans would also work very well here.