I improvise my recipe. What I do is bake about five small sweet potatoes at 400 degrees for an hour, let them cool and take the skins off, and add them to my classic biscuit recipe -- before I add the liquid. Mix them in with a pastry blender. You will need very little milk or buttermilk -- as the sweet potatoes are very moist. The dough is sticky...but the outcome is a triumph. So I mix 2 cups self rising White Lily flour with two teaspoons of sugar and teaspoon of salt. I cut in 1/4 cup crisco - then using the pastry blender..blend in the flesh of baked sweet potatoes. Add enough to give it a rich full color. Add about 1/4 cup buttermilk or milk. Add more flour if the dough is too sticky (no worries it happens)..when you get your dough ball turn it out a a very well floured surface kneed it four times and roll it out to 1/2 inch thick and cut your rounds. Bake 450 for 18 minutes.