To mill chestnut into flour, they are first dried over wood fire and this imparts the resulting product with a delicate and distinctive smoky aroma that make this flour pretty unique.
Being a nut´s flour, it doesn't contain gluten and so it is an useful ingredient for gluten-free pantries.
In Italy, chestnut flour is a traditional ingredient of the center-north portion of the peninsula. In Tuscany, notably, chestnut flour is used in a savory-sweet cake called Castagnaccio (castagna being the Italian for chestnut).
This cake is usually enriched with flavorful extra-virgin olive oil, pine nuts and rosemary but the main variation point in local recipes revolve around the use of cocoa powder in it.
Chestnut flour, with its deep rich sweet and smoky aromas, is just a perfect companion to chocolate and the use of a little cocoa powder in the Castagnaccio can only do it good, in my opinion.
I personally, simply adore rosemary in my Castagnaccio. When baked to crispy perfection, this herb lends its heady green-field aromas to this earthy densely satisfying cake; a perfect reminder of Tuscan sunbathed fields.
Try it once, and you will be hooked. You have been warned!