'- 500 gram cooked and mashed sweet potato (from about 2 medium size sweet potatoes)- 2 tablespoon sugar- 2 tablespoon milk powder- 1/4 teaspoon salt- 1/2 teaspoon cinnamon powder- 30 gram unsalted butter, room temperature- 1 egg yolk, lightly beaten, for egg wash- 1/2 teaspoon black sesame seeds, for sprinkles

1. Preheat oven to 350 Fahrenheit (180 Celsius). Line a baking sheet with parchment paper.2. In a mixing bowl, mix together mashed sweet potato, sugar, milk powder, salt, cinnamon powder, and butter until smooth.3. Divide the sweet potato mixture into 16 portions. With a piece of saran wrap, shape each portion into a ball, and arrange on the prepared baking sheet.4. Brush the top of each ball with egg yolk, and sprinkle with black sesame seeds.5. Bake in preheated oven for 45 minutes, or until golden brown. When done, the cake should have a golden crust with soft center.6. Remove from oven, and cool slightly before serving.