Preheat oven to 350 degrees. In a saucepan, combine the apple cider, cinnamon stick and mulling spices. Boil the mixture until it is reduced to about 1/4 cup and let it cool.
In a bowl whisk the pumpkin puree, eggs, oil, brown sugar, orange zest and the cooled reduced cider. Into a mixing bowl, sift together the flour, baking powder, salt, baking soda, mace, cinnamon and ground cloves. Add the chopped walnuts and stir the batter until it is just combined.
Transfer batter to a well-buttered 8-1/2x4-1/2-inch loaf pan. Bake the bread on the middle rack of the oven for about 1 hour, or until a toothpick inserted in the center comes out clean. Cool the bread in the pan.