Chop the yellow and green zucchinis and the bananas into small pieces and blend them in a mixer. In a bowl, take refined flour, baking soda, baking powder, cocoa powder, grated dark chocolate, sugar, brown sugar, raisins and grated orange peel. Mix these with the already prepared banana zucchini mix. Add milk to the mixture and blend it. Coat a baking tin with oil and pour chocolate mix into it. Bake it in a pre heated oven at 225 C for 30 to 35 minutes. Remove after baking and transfer it to a serving plate. Serve the sliced cake, garnishing with olive oil, grated dark chocolate, cocoa powder, powdered sugar and grated orange peel.