I started making these years ago when living in Japan, and I was searching for baked goods that I could pull off in our teeny-tiny convection oven. Scones were an easy win. These are lightly adapted from Love & Olive Oil's Pumpkin Scones with Cinnamon Sugar Glaze, and have remained in regular rotation -- even after I got back to a regular-sized oven.
For the sweet potato purée, you'll want to bake at least one medium-sized sweet potato until soft. I normally bake a few small one or two medium/large ones -- to account for any bad spots you might get, and so I have extra purée, I almost always want to bake a second batch in a day or two.
I blitz the cooked sweet potato flesh in my mini food processor to get it really smooth. I'm sure mashing it well with a fork would work just as well if you are not burdened with perfectionist tendencies. —Lindsay-Jean Hard