I've been on something of a biscuit kick, with the classic buttermilk biscuits in my cookbook, a yogurt-based alternative here on Serious Eats, and even an angelic variation made with plain milk, yeast, and an overnight rise. That's because biscuits aren't about having one be-all, end-all recipe, so much as having an arsenal of recipes that fit a variety of occasions. And sweet potato biscuits are certainly the most fun and colorful option of all.
The classic recipe is the result of Southern thrift and ingenuity, allowing a cheap and sturdy root vegetable to take the place of something more perishable like milk; sweet potato purée also helped make up for the lack of browning that can sometimes plague biscuits made with non-dairy fats like shortening or lard. So far as I can tell, the goal wasn't to create a new flavor of biscuit so much as a new path to a familiar goal: a tender, light, and fluffy accompaniment to any meal.
To get started, you'll need some sweet potato purée. How you acquire it hardly matters; boil a sweet potato up for the occasion, toss one in the microwave, roast one 'til fork tender, raid the fridge for leftovers, whatever! At home, I tend to make sweet potato biscuits after I've roasted one too many sweet potatoes for dinner the night before.
However you go about it cooking it, squeeze the tender sweet potato from its jacket, and mash the flesh with milk or water in a bowl; this loosens up the purée so the dough isn't too stiff down the road, which could inhibit its rise. Blitz the sweet potato and liquid with an immersion blender until silky smooth, or mash the mixture with a fork for a more rustic presentation that will leave bits of sweet potato flecked throughout the dough (my personal favorite).
This step can be done at the last minute, or the thinned purée can be held in the fridge up to a week in advance—a nice make-ahead option if you're so inclined. Otherwise, the dry mix for the biscuits will be prepared with the same method I use for plain, homemade biscuits as well as angel biscuits, with chunks of cold butter roughly incorporated into the dry mix, then hydrated with a liquid—in this case, that thinned sweet potato purée.
Like cultured buttermilk or yogurt, sweet potato purée is thick enough that a ton of the stuff can be incorporated into a dough without turning it into a sticky mess. In fact, the mixture may seem crumbly and dry at first; resist the temptation to add any extra liquid and simply keep kneading until the dough comes together and no flour is left at the bottom of the bowl.
Once the flour is fully incorporated, it pays to use a gentler touch. As with my other biscuit recipes, I turn the dough onto a lightly floured surface where I pat it out, fold it in half, and repeat the process two more times, for a total of three folds.
It's a gentle way of handling the dough, more quantifiable than kneading when it comes to developing enough gluten to hold the biscuits together, and smarter, too, since folding develops layers within the dough. In turn, those layers provide a natural fault line for splitting the baked biscuits in half, so they'll be easy to sandwich around anything from fried eggs to country ham. If you have trouble visualizing the process, the method for my yogurt biscuits is exactly the same, even if the dough looks rather different.
After the last turn, pat out the dough until it's about three-quarters of an inch thick, then cut into one-and-three-quarter-inch rounds (or whatever size you like; just bear in mind that the yield will vary).
Transfer the cutouts to a 10-inch cast iron skillet, and bake at 400°F until puffed and golden brown, about 30 minutes.
You can brush the biscuits with butter if you like, but I usually skip this step since it encourages more browning, making it harder to judge when the ochre-colored biscuits are done. And besides, these biscuits bake up plenty rich and buttery all on their own.
As with any biscuit, give these about five minutes to rest before serving. It's hard to wait, but fresh from the oven, the biscuits will be soft and easily compressed, making them seem gummy and dense. It only takes a few minutes for their crumb to set, and the result is a light and airy biscuit that'll still be plenty warm thanks to the insulation of cast iron.
Whether you're drawn to the recipe for its lack of buttermilk or the bright pop of color, sweet potato biscuits are a welcome addition to any meal, and just as delicious as they are beautiful to behold.