Before making the loaf cake, you'll need to cook the sweet potato. I prefer roasting them, but you can also boil them or use cooked canned sweet potato to save time. This step can be done the day before, as the mashed sweet potato needs to be cold for the scone dough.
To roast the sweet potatoes, preheat the oven to 425F. Wash and scrub your sweet potatoes, then pat and dry them with a towel.
Add the sweet potatoes to a tray and use a fork to pierce small holes in them. This allows steam to escape while roasting and prevents it from exploding.
Roast for 40-60 minutes or until cooked through. They are ready when a knife can be inserted without any resistance and they are soft inside.
Let the sweet potatoes cool for about 10 minutes. Then peel off and discard the outer skin.
Add the sweet potato flesh to a bowl and mash with a fork until smooth. The mashed sweet potato must be cold before using in the cake, so add to the fridge to cool completely before using.