I came up with this when we harvested our sweet potatoes from the garden and had a lot of undersized ones to use up. I had to come up with some way to use them so they wouldn't go bad. Turns out my family loves this bread. I used a persimmon bread recipe and substituted sweet potato for the persimmon pulp. This is especially good sliced, toasted and spread with butter!
Prep time includes the time needed to cook the sweet potatoes.
Heat the oven to 350°F and arrange a rack in the middle. Coat a 9-by-5-by-3-inch loaf pan with butter and flour; tap out the excess.
Combine the measured flour, salt, baking soda, baking powder, cinnamon, and nutmeg in a medium bowl and whisk to aerate and break up any lumps; set aside.
In the bowl of a stand mixer fitted with a paddle attachment, mix the sweet potato flesh, granulated sugar, and brown sugar on medium speed until well combined, about 1 minute. Add the melted butter and mix on low speed until smooth. Add the eggs 1 at a time, mixing until fully incorporated, then mix in the vanilla.
Stop the mixer and scrape down the sides of the bowl with a rubber spatula. On low speed add half of the reserved flour mixture, then 1/4 cup of the milk. Repeat with the remaining flour mixture and milk, mixing until just combined, about 1 minute. Remove the bowl from the mixer and fold in the nuts.
Pour the batter into the prepared pan and bake until a cake tester inserted into the center comes out clean, about 55 to 60 minutes. Let the bread cool in the pan for 15 minutes, then turn it out onto a wire rack to cool completely. It will last covered for up to 5 days. Freezes very well.