Egg Yolk: 60g
Sugar (for egg yolk): 15g
60g Sweet Potato Puree
250g Powdered Sugar 50g Butter 50g Heavy Cream 1. Steam the sweet potato chunks, then sieve while hot. 2. Mix the room-temperature softened butter and powdered sugar with a spatula. 3. Combine steps 1 and 2, and mix with a spatula. 4. Add the heavy cream gradually. 5. Whisk until smooth to form the sweet potato filling. 6. Mix egg yolks and 15g of granulated sugar, whisk until the color lightens.7. Mix salad oil and milk evenly, then gradually add to the egg yolk mixture and stir until combined.
8. Add 50g of sweet potato puree and mix well. 9. Sift in low-gluten flour and stir with a whisk in irregular directions until incorporated. 10. Add sugar to the egg whites in three batches, whipping until nearly stiff peaks form. 11. Fold one-third of the meringue into the egg yolk batter using a whisk. 12. Combine the remaining two-thirds of the meringue with the mixture from step 6, folding gently with a spatula until uniform. 13. Pour the batter into a baking pan and smooth the surface with a spatula. 14. Bake in the middle oven rack at 190°C top heat and 170°C bottom heat for about 15 minutes. 15. Once baked, remove the cake, transfer to a cooling rack, peel off the parchment paper from all sides, and cover with a clean baking paper when slightly warm.16. Flip the cake over, remove the parchment paper from the bottom, and make a diagonal cut on one side.
17. Spread the pre-prepared sweet potato filling evenly. 18. Lift the bottom parchment paper and roll up the cake. Refrigerate for half an hour to set. 19. After removing the parchment paper, you may decorate the top of the cake roll with an appropriate amount of sweet potato filling (or slice and serve directly).
