Preheat the oven to 350 degrees F. Butter and flour an 8 1/2- by 4 1/2-inch loaf pan and line the bottom with parchment paper. Bring 1/2 cup water to a boil in a small saucepan. Add the dates and set aside until cool. Drain.
Sift together the flour, baking powder, baking soda, pumpkin pie spice, and salt onto a piece of parchment paper. Set aside.
In a mixer fitted with the paddle attachment, cream the butter and brown sugar on high speed until fluffy, about 2 minutes. Add the eggs and sour cream and beat to combine, scraping the bowl down. Add the rum and vanilla and beat to combine. Add the flour mixture on low speed until just combined. Add the milk, increase the speed to medium, and beat until just smooth, about 15 seconds. Add the drained dates and the nuts and stir just until distributed.
Scrape the batter into the prepared pan. Bake until a toothpick comes out clean, 50 to 60 minutes. Cool in the pan on a rack for 15 minutes, then unmold and cool completely before slicing.
Recipe from "Farmhouse Rules" by Nancy Fuller. Copyright (c) 2015 by Fuller Farms, LLC. Used with permission by Grand Central Life & Style. All rights reserved.