Preheat the oven to 375 degrees F.
Place the raisins in a ramekin of water to soften for 20 minutes.
In a large mixing bowl, sift the chestnut flour. Add the sugar, orange zest, and pinch of salt, mix well and then gently start adding the water to the mix.
Using an electric hand mixer, beat the mixture well making sure to eliminate any lumps, then add 2 tablespoons olive oil, and half of the raisins and mix again.
Lightly oil an 11-inch pie plate with 2-inch sides with olive oil and pour in the batter it should be no more than 1/3-inch thick. Sprinkle the cake with rosemary leaves, the remaining softened raisins, walnuts, and pine nuts. Sprinkle with 1 tablespoon olive oil and bake for about 40 minutes.
This cake is very rooted in Tuscan traditions. There is no yeast, so it won't rise at all. The flavor is very specific, not really kid-friendly, but it grows on you as you develop your Tuscan palate. This flat-cake is usually served with wine and not with coffee, as you truly need to wash this one down!