1. Heat oven to 425°F.
2. Spray a baking sheet with cooking spray or line it with parchment paper.
3. In a bowl, mix together: Flour, Sugar, Baking powder, Salt, Baking soda, Nutmeg or Cinnamon
4. Grate the cold butter using a box grater, add the grated butter to the bowl. If you don’t have a box grater, chopping up the butter will be just fine!
5. Use a fork to mix until the mixture looks like small crumbs.
6. Do not use your hands. The butter should stay cold.
7. To make the mashed sweet potatoes, add potatoes to a large pot and cover with water (about 1 inch).
8. Bring to a boil and reduce heat to a simmer.
9. Simmer for 10-15 minutes until fork tender.
10. Drain potatoes and mash
11. Allow them to cool in the refrigerator or on the counter before the next step.
12. Make a small hole in the middle of the bowl, and add the mashed sweet potato and buttermilk. Stir until a soft dough forms. Some flour may not mix in yet.
13. Place the dough on a lightly floured surface (if sticky, sprinkle with a little flour).
14. Press the dough into a rectangle about 1 inch thick.
15. Fold the dough in half, and press flat again.
16. Repeat folding and pressing 3 more times.
17. Press the dough into a rectangle about ¾ inch thick. (Cut into 8 squares).
18. Place biscuits on the baking sheet, about 1 inch apart.
19. Bake for 13–15 minutes until lightly golden, let biscuits cool on the pan for 5 minutes.
20. Optional: Brush with melted butter and add a little salt.

Notes