Castagnaccio is often called a 'cake' in English translations, but it's really something else. It's something like a dense, thick crêpe (not quite as fluffy as a pancake), rather than a 'cake'. It's hard to describe, but a description is necessary for those that have never come across the texture of this ancient, rustic and unusual Tuscan delicacy before.
Tuscans don't have much of a sweet tooth and Castagnaccio is proof of this, as it mainly relies on the naturally sweet flavor of the chestnut flour and the raisins. Ancient versions of this recipe don't even include sugar, but today usually a few spoonfuls make their way in there to boost the sweetness ever so slightly -- but it's still, pleasingly, subtle. Some grated orange zest is often added to the batter, and the walnuts can be left out or replaced with more pine nuts. Serve it on its own or with a dollop of fresh ricotta and a glass of red wine or dessert wine. —Emiko
Combine chestnut flour, sugar, and salt in a bowl. Add the water, bit by bit, stirring to avoid lumps. You are looking for a batter that will run off the back of a spoon, much like pancake batter. Depending on the quality of the flour, you may need a little more or a little less water than called for to obtain this consistency.
When smooth, add 2 tablespoons olive oil to the batter and let the mixture rest for at least 30 minutes.
In the meantime, preheat the oven to 350º F (180º C) and soak the raisins in cold water for 15 minutes. Drain.
Pour the batter into a 12- by 8-inch (30- by 20-centimeter) baking dish lined with parchment paper. It should be no more than 1/3- to 1/2-inch thick (about 1 to 1.2 centimeters). Evenly scatter over the drained raisins, walnuts, and pine nuts. Finish with rosemary and the rest of the olive oil.
Bake for about 30 minutes or until you begin to see little cracks appear all over the top. Do not overbake or it will become very dry. Let cool in the pan then slice into squares and serve. This keeps well for a few days in an airtight container at room temperature (do not refrigerate as the texture becomes hard and rubbery).
The Australian-Japanese cookbook author has lived in Florence (where a visit to a cheese farm once inspired her to start a food blog) for over 10 years with her Tuscan sommelier husband and two kids. Her third cookbook, Tortellini at Midnight, is out now.