Wash the sweet potato thoroughly with the skin on and steam it.
Peel the cooked sweet potato and mash it finely.
Add plain yogurt, egg, and honey to the mashed sweet potato and mix.
Add baking powder and oatmeal, and mix until well combined.
Pour the batter into a cake mold.
Bake in an oven at 180°C for 25–30 minutes.
Let it cool, then cut into serving pieces.