Preheat the oven to 400°F or 200°C. Line your cake panwith parchment paper.Soak ⅓ cups raisins in a small bowl with hot water for 10 minutes.Add 2½ cups chestnut flour, 2 cups water, ¼ cups sugar, 2 tablespoons olive oil, and ⅛ teaspoon salt to a blender. Blend for two minutes or until smooth.
Take the blender pitcher off the blender and add almost all the raisins (drained from their soaking water), ¼ cups walnuts, and 3 tablespoons pine nuts.Set aside some raisins, walnuts, and pine nuts for garnishing.DO NOT BLEND; stir with a spoon to mix the ingredients.
Pour the mixture into the cake pan. Then, scatter the remaining raisins, walnuts, and pine nuts on top.Finally, add the needles from 1 sprig rosemary and drizzle with extra virgin olive oil.
Bake at 400°F or 200°C for about 35 minutes. Then, let cool down for 10 minutes, and remove from the pan. Cut and enjoy slightly warm or at room temperature.