Soak raisins and rosemary leaves in a small bowl of lukewarm water. Set aside.
Position oven rack to center position. Preheat oven to 350°F and grease a 9” pie pan with one tablespoon olive oil (or non-stick cooking spray). Set aside.
In a large bowl, combine chestnut flour, water, maple syrup, and remaining olive oil with a fork. Continue stirring until a smooth batter forms. If batter is too thick, add another tablespoon or two of water to thin slightly.
Drain raisins and rosemary leaves and pat dry. Add half of the raisins, walnuts, and pine nuts to batter and stir to combine.
Pour batter into 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!