Soak the raisins and rosemary leaves in a small bowl of lukewarm water. Set aside.
Preheat oven to 180°C/350°F/Gas 4 and grease a 9”/22cm pie pan with olive oil or non-stick cooking spray. Set aside.
In a large bowl, combine chestnut flour, water, honey, and olive oil with a fork. Continue stirring until a smooth batter forms. If the batter is too thick, add another tablespoon or two of water to thin slightly.
Drain the raisins and rosemary leaves and pat dry. Add half of the raisins, walnuts, and pine nuts to the batter and stir to combine.
Pour batter into the prepared pie pan and spread with a spatula to form a smooth, uniform layer. Evenly distribute rosemary and remaining raisins, walnuts, and pine nuts on top of batter.
Place pan in pre-heated oven and bake for 30-35 minutes or until the top is dried and starting to crack.
Remove from oven and cool slightly before cutting into thin slices and serving. Enjoy!