1. Preheat the oven to 350 F and line a standard sized loaf pan with parchment paper. In a large bowl, sift together the flour, baking powder, baking soda, cinnamon, nutmeg, ground ginger, all spice and salt. Whisk to combine.
2. In another bowl, whisk together the melted butter and brown sugar until the sugar is dissolved. Add the orange juice and eggs, and whisk. Add the milk and stir, followed by the grated zucchini and orange rind. Make a well in the center of the dry ingredients and pour the wet ingredients into the middle. Add the walnuts, and stir just until combined. Do not overmix! Empty the batter into the prepared loaf pan, and bake for 40-45 minutes or until a toothpick inserted in the center comes out clean. Remove the pan from the oven and allow to cool for 10 minutes in the pan before removing to a wire rack to cool completely.
3. Prepare the glaze. In a medium mixing bowl, stir together the powdered sugar, juice and zest. Add the cream, 1 tbsp at a time until the glaze is smooth but still fairly thick. Drizzle the glaze all over the cooled loaf. Serve immediately!

I store the leftovers in the fridge, in order to prevent the glaze from melting into the loaf. If storing at room temperature, keep the loaf in an airtight container for 2-3 days. Loaves can be frozen (preferably pre-glazed) for 2 months.