Pre-heat the oven to 180° C (356° F) and soak raisins in warm water for about 10/20 minutes.
Sift the chestnut flour in a bowl and add a pinch of sea salt.
Add the water and mix slowly with a whisk. Add a tablespoon of Extra Virgin Olive Oil and keep whisking.
Put a baking sheet into the baking tray and grease it with oil.
Add a fistful of raisins (previously squeezed), pine nuts and walnut kernels, and mix.
Pour the dough in the baking tray and flatten it. Add the remaining walnuts, pine nuts and raisins and the two rosemary twigs. Sprinkle with a bit of extra virgin olive oil the surface of the dough.
Bake for about 25/30 minutes until you see small cracks on the surface and till it gets a chocolate brown colour.
Cut in slices and serve.