Preheat oven to 375°F. Grease a standard 9 x 5-inch loaf pan, or 3 small loaf pans. Set aside.
In a large bowl, whisk or sift together the flour, baking powder, cinnamon, salt, nutmeg, ginger, allspice, cloves, and orange zest.
In a separate medium bowl, whisk together the eggs, brown sugar, milk, oil, and vanilla extract.
Add the wet ingredients to the dry ingredients. Use a wooden spoon or rubber spatula to stir just until the ingredients are combined. Do not over-mix.
Fold in the dates and walnuts.
Transfer the batter to the prepared loaf pans.
In a small bowl, stir together the granulated sugar and cinnamon for the topping. Sprinkle on top of the batter.
Bake for 25-30 minutes for the mini loaves, or 55-60 minutes for a standard-size loaf. The bread is done when a toothpick inserted in the center comes out clean, or with a few moist crumbs. Tent the larger loaf loosely with foil during the final 20-30 minutes if it starts to get too dark on top before it's cooked through.
Cool in the pan for about 5-10 minutes, and then transfer to a wire rack to cool completely before slicing.