Sweet Potato Custard Bread (Studio Ghibli Soot Sprite) (Video)

These dark chocolate buns stuffed with sweet potato custard are not only adorable but also extremely delicious! They are made to look like the soot sprite character from the Japanese, Studio Ghibli animated films, “My Neighbor Totoro” and “Spirited Away”.

These dark chocolate buns are stuffed with a delicious molten, sweet potato custard and is perfect for breakfast! If you are wondering why these custard buns are black and have eyes on them, it is because they resemble the soot sprite character from the Studio Ghibli films. Studio Ghibli is a Japanese animation studio that produces ethereal movies that are pretty nostalic for people of all ages. The movies are mainly targeted towards children, but people of all ages watch them as the combination of scenery, music, and story line always mesh so well together. The soot sprite, or dust bunnies, appear in two films and quickly became fan favorites because of how cute and enigmatic they are.

*To make the soot color, I used this specific black cocoa powder, which is literally pitch black. Black cocoa powder may be difficult to come by, so I had to purchase mine online. As alternatives, you may use:

  • Hershey’s Special Dark cocoa powder, which is a deep dark brown and not entirely black.
  • Black food coloring
  • Charcoal powder, which will result in a dark grey bread.

In “Spirited Away”, the soot sprite are given a Japanese star-shaped candy called Konpeito. To imitate this candy, I used this specific star sprinkle. These sprinkles can be found at local grocery stores but the Konpeito candy is likely found in Asian grocery stores only.


The sweet potato custard is like any other custard, but includes Japanese sweet potato, which is highly nutritious and acts as a thickener and natural sweetener. There are yellow, white, purple, and orange-fleshed Japanese potatoes. All of these can be used, but I used white sweet potato because it was what I had at home.

This recipe has several steps, but is very rewarding and is great as gifts for people, especially those who love Studio Ghibli!

Sweet Potato Custard Bread (Studio Ghibli Soot Sprite)


yield: 6 buns

For sweet potato custard:

  • 250 g. milk (any fat percentage works)
  • 42 g. granulated sugar
  • 34 g. egg yolks (2 egg yolks)
  • 20 g. cornstarch
  • 4 g. unsalted butter
  • 200 g. Japanese sweet potato, cooked and mashed (any color flesh works)
  • 4 g. vanilla extract

For bread:

  • 68 g. lukewarm water (Not too hot or too cold since the yeast may die.)
  • 2 g. instant yeast
  • 132 g. bread flour
  • 5 g. milk powder
  • 11 g. sugar
  • 1 g. salt
  • 12 g. black cocoa powder (See above for substitutions)*
  • 16 g. beaten egg
  • 13 g. unsalted butter, softened
  • 1 beaten egg for egg wash

For decoration:

  • 10 g. white chocolate
  • 2 g. black cocoa powder
  • Colored sprinkles


  1. To make the sweet potato custard, heat a pot over medium heat and add the milk and sugar. Whisk until dissolved. Add in the yolks, cornstarch, butter, sweet potato, and vanilla extract and whisk constantly until the mixture thickens and comes to a boil. The custard will thicken more as it cools. Set aside to cool and thicken.
  2. For the bread, dissolve the yeast and and warm water in a small bowl. Set aside for 5 min.
  3. In a stand mixer, add in the bread flour, milk powder, sugar, salt, and cocoa powder. Mix until combined. Then add in the yeast mixture and egg and knead for 10 min on low speed (Speed setting 4). You may knead by hand for 15 min.
  4. After 10 min, add in the softened butter and knead for an additional 5 min. You may knead by hand for 8 min.
  5. Place the dough in a lightly oiled bowl and allow to rise for 1 hour in a warm place.
  6. After 1 hour, divide the dough into 6 equal pieces and roll into balls. Place on a baking try with parchment paper or a baking mat. Make sure the ball pieces are well-spaced as they will double in size. Cover with a towel or foil. Allow to rise in a warm place for another hour.
  7. Preheat oven to 375 F.
  8. Lightly brush the bread with egg wash and bake in the oven for 12 min. at 375 F. Remove from oven and allow to cool on a cooling rack.
  9. To make the soot sprite eyes, microwave the white chocolate for 15-20 sec. or until melted. Take a sheet of paper and draw two small ovals. Place a sheet of parchment paper over this paper and use a chopstick or any slim tool to fill in the ovals using the white chocolate. You will need 12 ovals for the 6 breads, but I make extra just in case any turn out bad.
  10. Place this on a pan flat surface and freeze for 3-5 min.
  11. Using the leftover white chocolate, add 2 g. black cocoa powder to make the pupils. Remove the tray from the freezer and use a chopstick or slim tool to dot the pupil onto the white chocolate eyes. Freeze until ready to use.
  12. Place the sweet potato custard in a piping bag with a circular piping tip.
  13. Use a stick to poke a deep hole on the side of the buns. Place the piping bag inside and pipe the custard into the buns.
  14. To place the eyes on the buns, dot on some leftover custard and attach the eye on the buns. Repeat for the rest.
  15. Sprinkle the buns with sprinkles and enjoy!

NutritionLabel (8)

*Nutrition facts are estimates

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