Crispy and flaky, with a smooth, silky filling, Japanese Sweet Potato Pie is my all-time favorite Japanese pastry. Best enjoyed with a cup of coffee or black tea, this sweet potato pie is light, but rich, making it the perfect afternoon indulgence.
Gather all the ingredients. Preheat oven to 400 ºF (200 ºC). Place 1 sheet of pastry on a baking sheet that has been lined with parchment paper. Put another pastry sheet on a different sheet of parchment paper. Defrost for 10 minutes at room temperature.
Peel the sweet potato and cut in half lengthwise. Then cut into smaller chunks so they will cook faster.
In a pot, put sweet potato and cover it with water. Bring it to a boil and cook until a skewer goes through the potatoes smoothly, about 12-15 minutes. Drain water completely and transfer to a large bowl.
Use a potato masher or fork to mash the sweet potato. Add sugar and butter and keep mixing.
Add egg yolk and heavy whipping cream and mix well.
Beat the egg in a small bowl and brush top of the pastry so it will turn nice golden brown. Sprinkle black sesame seeds on top.
Bake for 20-25 minutes, or until golden brown. Let cool a bit and ready to serve in 10 minutes.
You can freeze the baked and cooled pies. Wrap them in aluminum foil and put them in a freezer bag. To serve, reheat the pie at 350 ºF (180 ºC) for 10-15 minutes, until crisp and flaky.