Thickly peel off the skin from the sweet potato, rough chop, then soak for up to 10 minutes in water. Drain, wrap loosely in plastic wrap, then microwave until tender.
After microwaving for 6 to 7 minutes at 500W, you should be able to easily skewer the potato all the way through. Remove the plastic wrap, then cool.
Combine the ● ingredients in a food processor (or mixer), then process for 2 to 3 minutes on full strength!
When it gets white like shown in the photo, add the cooled sweet potato, then process again on full strength.
The lumps from the sweet potato should disappear and the batter should become even. It should be thick.
Put the batter in a rice cooker, sift in the flour and baking powder, then fold with a rubber spatula while spinning the bowl around.
When the batter reaches an even consistency, remove the batter from the sides with a rubber spatula, then turn on the switch!
When the rice cooker signals that it is done, pierce the cake with a skewer. If it comes out clean, then it's done; if it doesn't, then switch on the rice cooker (or bake?) 1 or 2 more times.
When it's done, turn it over onto a rack. Before taking it out of the rice cooker, shake the bowl to make it release easier.
It should have a nice golden surface and be fluffy and rich! You can serve it right away or let it sit overnight.
I baked it in an oven! I filled muffin molds with the batter, then baked it for 20 minutes at 190°C. They rose to be as fluffy as in this photo.
Here is a variation on this recipe: Butter-Free Rice Cooker Chocolate Cake (Recipe ID: 2017250)
And here is a Japanese style one: Adzuki & Sesame Seed Japanese Style Cake in the Rice Cooker (recipe ID: 2032976)
Story Behind this Recipe
I came up with an easy way to bake sweet potato cake, since I don't have the time for careful conventional baking.
This recipe doesn't require any complicated techniques. Just leave it up to your food processor and rice cooker. Either olive oil or vegetable oil is fine. You can also try using a half-half mixture. The amount of steaming may depend on your rice cooker, so keep an eye on it and adjust as necessary. This can also be baked in an oven.