1. Soak 5g of butterfly pea flowers in 40g of hot water, and filter out butterfly pea flowers after soaking.
2. Eggs should be separated from egg whites, yolks, and egg whites and put them in oil-free and water-free containers.
3. Add white sugar A and milk powder to the butterfly pea flower water and stir evenly. Beat until the white sugar melts.
4. After completing step 3, pour step 3 into the egg yolk, and then add corn oil.
5. Sift in low-gluten flour, then stir slowly. The prepared egg yolk paste is set aside to stand for 10 minutes.
6. Add white sugar B to the egg white.
7. Use an electric power generator to blow from low speed to high speed to wet foaming.
8. Put one third of the whipped meringue spoon into the egg yolk paste and mix evenly.
9. Stir evenly, then pour in the remaining meringue, mix and stir evenly.
10. Cover the baking pan with greased paper, pour the batter evenly and shake the baking pan to defoam.
11. Preheat the oven in advance, top the heat to 190 degrees, and lower the heat to 150 degrees. Place it on the middle floor and bake for 20 minutes.
12. Add sieved powdered sugar to the whipped cream.
13. Use an electric whisk to whip the whipped cream at a low speed until the whipped cream appears lines.
14. Spread the whipped cream on the cake base after inverted and unmolded and let cool.
15. Use a rolling pin to slowly roll up the cake, and put the rolled cake in the refrigerator for half an hour to set the shape.
