Mix all the blender ingredients in a high-power blender until creamy.
Mix the dry ingredients in a large mixing bowl.
Add the blended ingredients to the dry ingredients and incorporate with a spatula (if you use chestnut flour sift it before, as it tends to form clumps).
Add the chopped chocolate and fold it into the batter.
Pour the batter into a lined loaf pan and bake at 180C / 350F for about 55 minutes, until it is no longer soft to touch.