Preheat oven to 180 degrees C. Grease baking trays.
In a large bowl, cream together the butter and brown sugar until smooth, then beat in the egg. Combine the flour, baking powder, salt, cinnamon, nutmeg and cloves; stir into the creamed mixture alternately with the milk. Finally, mix in the zucchini, walnuts, raisins and orange zest. Drop by heaping spoonfuls onto the prepared baking trays.
Bake for 12 to 15 minutes in the preheated oven, or until the edges are lightly browned.