A slice of chestnut flour cake

How to make castagnaccio, Tuscan chestnut flour cake

Traditional Tuscan chestnut flour cake, castagnaccio in Italian, is beautiful in its simplicity. It needs no sugar as chestnut flour is naturally sweet and it is made with only four ingredients, plus water and salt — chestnut flour, raisins, pine nuts, and olive oil.

But calling it a cake may be misleading. Made with raisins and nuts and with no added sugar and very little fat, it’s arguably more of a healthy energy bar in the shape of a cake than a cake. It seems more suited for a long hike than the dessert table. Chestnut flour also has a distinct rustic flavor that some people simply don’t like.

That said, it’s loved by many folks too. I gave half this cake to my boyfriend’s Italian mother and she loved it. Perhaps chestnut flour is an acquired taste.

Pine nuts are also always pricey and this recipe uses a lot of them. I spent about 15 bucks on the pine nuts for this cake and I’m in Italy. The recipe probably made more sense back in the day when the pine nuts came from the pine tree in your own backyard. Feel free to switch out some of the pine nuts for less stately walnuts.

Castagnaccio, Tuscan chestnut flour cake

I always bake with a kitchen scale and measure my ingredients in grams. I try to write out the recipe in cups as I know many people prefer it this way but there could be subtle discrepancies, especially with flour.

  • 500 g (4 1/2 cups) chestnut flour
  • A pinch of salt
  • 500 g (2 1/3 cups) water, plus another 50 g (1/3 cup) more if needed
  • 120 g (1 cup) raisins
  • 100 g (3/4 cup) pine nuts (or blend with walnuts)
  • 1 sprig rosemary, needles only
  • Drizzle of olive oil
  1. Preheat oven to 350° F (180° C) and oil a round baking pan (9 or 10 inches in diameter) with olive oil.
  2. Soak the raisins in water for 5 minutes and drain.
  3. Meanwhile, blend the flour and salt in a mixing bowl and slowly add the water while whisking by hand. Be careful not too add the water too quickly. You may need to add a bit more water, up to another 1/3 cup (50 g) but add it slowly and cautiously. The batter should not be too liquidy and should fall like a ribbon.
  4. Add most of the pine nuts and raisins, reserve about 1 tablespoon of each, and blend.
  5. Pour the batter into the oiled pan and add the reserved pine nuts and raisins on top, along with the rosemary.
  6. Drizzle with olive oil and bake for 25-30 minutes. Be careful not to overcook. It can become too dry very quickly. Check if it is done with a toothpick or a thin knife. It should be slightly moist and firm but still soft. The top will crack but be careful that the cake and the raisins and nuts on top do not burn.
  7. Cool completely and serve.

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