1. Preheat oven to 425°F (220°C) and line a baking sheet or heat a cast-iron skillet.

2. In a large bowl whisk flour, baking powder, baking soda, and salt until combined.

3. Add cold cubed butter and cut into flour with a pastry cutter until mixture resembles coarse crumbs.

4. In a separate bowl mix mashed sweet potatoes, sourdough starter, honey, and 1/3 cup buttermilk until smooth.

5. Pour wet ingredients into dry and fold gently, adding remaining buttermilk only if needed.

6. Turn dough onto floured surface and pat into a 1-inch thick rectangle.

7. Fold dough in half, rotate, and repeat folding two more times, then pat back to 1-inch thickness.

8. Use a floured 2.5-inch biscuit cutter to cut rounds, placing them close together on the sheet.

9. Brush tops with melted butter or buttermilk if desired.

10. Bake for 15–18 minutes until golden and risen.

11. Cool on a rack for 5 minutes before serving.

12. Store leftovers in an airtight container at room temperature for up to 2 days or freeze for longer storage.