Preheat your oven to 200℃. Peel the baked sweet potatoes and mash.
Using the masher, incorporate the butter, brown sugar, eggs, milk, and 1 tablespoon of the sesame seeds to Step 1. Once these have all been added, switch to a rubber spatula.
Sift together the flour and baking powder and mix into the Step 2 mix with the spatula. Put in a plastic bag.
Cut the end of the plastic bag and use it to squeeze out the batter into donut shapes on a baking pan lined with a cookie sheet. Top with sesame seeds and bake at 200 ℃ for 17 minutes.
For my first attempt, I baked at 180℃ for 18 minutes and they didn't really get that 'baked' look.
Story Behind this Recipe
I found a recipe card for "soft and chewy oven-baked donuts" at the supermarket and tried to recreate them using sweet potatoes my parents' grew.
I recommend Narutokintoki sweet potatoes as they're really fluffy and only requires about 100 ml of milk to soften. When pipping out the dough, you want the doughnuts to have a solid shape, so please adjust the amount of milk you use accordingly. If you sprinkle a bit of brown sugar (or white sugar) on top of the doughnuts, the surfaces will become crispy.