Here's a recipe for "Osatsu Butter," a sweet potato treat with a fluffy and chewy texture. Peel the sweet potatoes and soften them in the microwave, then mash them until smooth. Add sugar, potato starch, and milk and mix well. If the mixture is too thick, add more milk to adjust the consistency, then shape it into circles about 1.5 cm thick. Lightly coat a frying pan with vegetable oil and cook the patties until golden brown on both sides. Turn off the heat and coat with butter. It's best to eat them while they're hot.