Preheat the oven to 350°F Grease the bottom and sides of a 9 by 5-inch loaf pan with oil, and line the bottom with parchment paper.
Combine the milk, honey, and molasses in a small saucepan. Set over medium heat and heat the mixture without boiling, stirring with a spatula until dissolved. Set aside and let cool as you go on with the recipe.
In a large mixing bowl, combine the flours, baking powder, baking soda, salt, and spices. In a small bowl, combine the ginger and/or orange peel, if using, with 2 teaspoons of the flour mixture and set aside.
Form a well in the centre of the flour mixture. Pour in the milk mixture slowly and whisk in a circular motion, starting from the centre, until all the flour has been incorporated - the batter will be thin. Fold in the ginger and/or orange peel, if using. Pour the batter into the prepared loaf pan and bake for 40 to 50 minutes, until the surface is brown and a knife inserted in the centre comes out clean.
Transfer to a rack to cool for 20 minutes. Run a knife along the sides of the pan to loosen the loaf, and unmould. Let cool completely, wrap in foil, and let rest at room temperature until the next day.