Preheat the oven to 180°C (350°F).
Grease a round cake pan (26 cm). I use a silicon pan and spray with vegetable cooking oil.
In a bowl, whisk the orange juice,(leave aside 4 tbsp of juice) with the sugar, and the olive oil until the sugar dissolves.
In a different (smaller) bowl, add the cinnamon and cloves, mix in the bakong soda, and the extra orange juice, mix until it creates a foam.
Add the baking soda mix to the orange juice mix. Still well.
Sift the flour and gradually fold it into the wet mixture.
Stir in the raisins, walnuts (and chocolate if using).
Pour the batter into the prepared baking tray and smooth the top.
Bake for 55-60 minutes, or until a skewer inserted in the center comes out clean.
Allow to cool very well, then dust with powdered sugar before serving.