Heat oven to 425°F and line a baking sheet with parchment.
Whisk flour, sugar, baking powder, baking soda, salt, and cinnamon in a large bowl.
Cut in the cold butter until the mixture looks like coarse crumbs with pea-size bits.
Stir in mashed sweet potato and cold buttermilk just until a shaggy dough forms.
Turn dough onto a lightly floured surface and gently bring it together without overworking.
Pat into a 1-inch-thick slab, fold it over itself twice, then pat to about 3/4 inch thick.
Cut biscuits with a 2 to 2 1/2-inch cutter, pressing straight down. Reroll scraps gently.
Arrange close on the sheet, brush tops with buttermilk, and bake 12–15 minutes until golden.
Notes
For a savory twist, fold in 1/3 cup chopped toasted pecans or a pinch of chopped rosemary. Sweet finish: brush hot biscuits with melted butter and a drizzle of maple syrup. To make ahead, freeze cut biscuits on a tray, then bake from frozen at 425°F, adding 2–3 minutes. Leftovers reheat well in a 300°F oven for 6–8 minutes.This recipe is an original creation inspired by classic Sweet Potato Biscuits Bliss flavors. All ingredient ratios and instructions are independently developed.