In Siena, where the chestnut cake is part of a rich tradition of cake making, the bakers keep their secrets to themselves, not least with the centuries old methods of making castagnacci. The big secret is the ratio of liquid to chestnut flour, the next is the oven temperature, then the baking time, and then the amount of olive oil. The difference is a hard (less liquid) or soft (more liquid) cake, an even bake and a crisp crust.
- 700 ml water
- 500 g chestnut flour
- 10 g rosemary, fresh, chopped small
- 90 ml olive oil
- 100 g pine nuts, whole
- 100 g raisins, soaked in water, drained, dried
- 75 g walnuts, crushed (optional)
- 50 g candied fruit
- Salt, pinch
Preheat oven to 200ºC.
Sieve the flour into a large bowl, pour the water into the bowl in a drizzle, whisking constantly to eliminate lumps.
Separate a tablespoon each from the pine nuts and raisins, set aside.
Add salt, candied fruit, pine nuts, raisins and walnuts to the batter.
Grease a 30 centimetre round baking tin with 60 grams of oil, pour in the mixture, sprinkle surface with rosemary and remaining nuts and raisins, finish with remaining oil.
Bake for 35 minutes.
The cake should have a dark chestnut colour, a crispy cracked surface. Cut, it will be soft and slightly moist.