1. Prepared ingredients.
2. Separate the egg whites and yolks.
3. Add egg yolks, milk, salad oil, and sugar to beat evenly.
4. Sift the low-gluten flour and add it to the egg mixture.
5. Mix well and set aside.
6. Add white sugar to the egg whites and beat them until soft foaming, and the whisk can pull out the long hooks.
7. Add the beaten egg whites to the egg yolk batter three times and mix well.
8. Pour the completely mixed cake batter into the baking pan.
9. After preheating at 170°C, bake the middle layer for 20 minutes, then let it cool down.
10. The purple sweet potato is cooked in the microwave and peeled.
11. The purple sweet potato is pressed into a puree and sieved.
12. Add blueberry sauce, mix well and set aside.
13. It is easier to make a knife on the surface of the cake, and it is easier when it is rolled, and it is not easy to crack.
14. Apply purple potato mash.
15. Roll it up and put it in the refrigerator for more than 2 hours.
16. Slice and taste.
Tips:1. The addition of blueberry sauce is to make the purple sweet potato brighter, and it can also increase the sweetness.
2. Oil paper should be placed on the baking tray for baking cakes, pay attention to observe during the baking process, and adjust the temperature.
