Preheat the oven to 450°F. Line a baking sheet with parchment paper.
Wash the sweet potato and then poke the potato several times with a fork. Place it in a microwave safe bowl and add 2 tsp of water to the bowl. Cover with plastic wrap and cut a slit in the top. Microwave for 3 to 5 minutes, until soft and the skin is loose. Let cool.
In a large bowl, whisk together the flour, brown sugar, baking powder, baking soda, salt, and cinnamon.
In a separate bowl, stir together the syrup, applesauce, and buttermilk.
Once the sweet potato has cooled, peel and mash well with a fork. Transfer the mashed sweet potato to the wet ingredients and stir to combine.
Add the sweet potato mixture to the flour mixture and stir just until the dough comes together, being careful not to overmix.
Lightly flour a clean surface and using clean hands transfer the sweet potato dough to the surface. It is very important to keep the surface covered lightly in flour, as the dough will be sticky. Gently roll the dough out to a 10-inch-diameter about ½ inch thick and use a 2 ½-inch biscuit cutter or the rim of a juice glass to cut out biscuits. Gather the scraps and re-roll to cut out more biscuits. You should get 10 biscuits.
Transfer the biscuits to the prepared baking sheet. Bake until slightly browned on the edges, 24 to 28 minutes. Serve warm.