The Best Sweet Potato Biscuits

Ingredients

• 9 ounces all-purpose flour, such as Gold Medal
• 1 tablespoon baking powder
• 2 teaspoons Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight Diamond Crystal kosher salt
• 1/2 teaspoon baking soda
• 4 ounces cold, unsalted butter, cut into 1/2" cubes
• 9 ounces sweet potato purée, from one large sweet potato, see note
• 3 ounces milk, any percentage will do

Directions

1. Set an oven rack in the lower-middle spot, and heat the oven to 400 degrees F. If your kitchen is above 75 degrees F, use your usual hot-kitchen baking tricks before you begin; biscuits appreciate the same cool-hand treatment as pie dough. Into a medium bowl, sift the flour, baking powder, baking soda, and salt, then whisk the mixture thoroughly, which can take up to 1 minute. Drop in the butter, toss it through the flour to separate the cubes, and press each piece until flat. Keep pressing and rubbing the butter into the flour until it is mostly worked in, with a few bigger bits about the size of Cheerios still hanging around. You can do this in a food processor instead with 4 or 5 pulses, but stop before the mixture gets too fine. At this point, you can chill the prepared mixture in an airtight container for up to 3 weeks, then continue with the recipe from here.
2. Use a fork to mash the sweet potato purée with the milk, or make it completely smooth with an immersion blender. Scrape it into the dry mixture in a large bowl, and use a flexible spatula to fold everything together until the liquid is absorbed. It will look dry and shaggy at first, but stay with it until the dough gathers itself into a rough ball. Turn the dough out onto a lightly floured work surface.
3. Using your hands, pat the dough gently into a rough square about 1/2-inch thick, then fold it over in half. Do that same pat-and-fold move twice more, for a total of 3 folds, adding just enough flour to keep the dough from sticking to your hands. Pat the dough out one last time until it is 3/4 inch thick. Brush off extra flour if you need to, then cut the dough into 1 3/4-inch rounds and place them in a 10-inch cast iron skillet. Press the scraps together, pat and fold them once, and cut out as many extra biscuits as possible. Gather the last scraps and shape them by hand into one final biscuit.
4. Bake the biscuits until they have risen nicely and turned golden brown, about 25 minutes, or a bit longer if you cut them thicker than 3/4-inch. Let them rest for about 5 minutes so the crumb can settle, then serve however you like, with soup, stew, shortcake fixings, or breakfast sandwich fillings. Leftovers can be kept for up to 1 week in an airtight container; when you want to serve them, split the stale biscuits in half, brush them with melted butter, set them on a baking sheet, and broil until golden brown, then add jam.