I've been chasing the Sweet Potato Biscuit for years, and this is by far the best one I've tried. This is probably because it's not a biscuit at all--it's a quickbread, or a Muffin Method bread in Alton Brown's taxonomy. The large amount of baking powder is necessary to lift the heavy dough. You don't want to stir the sweet potatoes into the dough too well--you want little bits sticking out. The cranberry butter is great with them, but my favorite topping is just plain honey.
Sweet Potato Biscuits
(adapted from Screen Doors and Sweet Tea by Martha Hall Foose)
1 cup mashed sweet potato
2/3 cup milk
1/2 stick butter, melted
2 tbsp sugar
1 1/4 cup all purpose flour
1 1/2 tsp kosher salt
3 1/2 tsp baking powder
Heat the oven to 450 and line a sheet pan with parchment. Mix the potatoes, milk, butter, and sugar in one bowl. In another, mix the flour, salt, and baking powder. Add the wet team to the dry team and stir until combined. Using a #40 disher or a couple of spoons, lay the dough out in pieces a little bigger than a golf ball on the parchment. Bake for 12-15 minutes, watching closely for burning on the bottom. Serve hot, and in the unlikely event there are any left, store them in a Ziploc in the fridge and heat in the toaster oven as needed.
1 stick butter, softened
1/2 cup leftover cranberry sauce
1 tbsp honey
Stir together. Serve alongside biscuits.