Preheat the oven to 350 degrees F. Grease and flour one 9 x 5-inch (8-cup) loaf pan, or line the bottom with waxed or parchment paper.
Melt unsalted butter, then pour into a large mixing bowl and let cool slightly. Add sugar, vanilla, salt, sour cream, egg and stir together until smooth. Add baking soda and baking powder (in pinches to break up any lumps) and whisk in.
Stir in flour just until combined. Stir in chocolate chips. Scrape the batter into the pan and spread evenly. Bake until a toothpick inserted in the center comes out clean, 40 to 45 minutes. Let cool in the pan on a rack for 10 minutes. Slide a slim knife around the cake to detach it from the pan. Invert the cake and peel off the paper liner, if using. Let cool right side up on rack. Frost with Quick White Icing (www.familycircle.com), adding the zest of 1 small orange and using 2 tablespoons orange juice as the liquid. Makes 8 servings.