3 ingredients sponge cake

I got this recipe from a Japanese pastry book.
- 3 eggs (weight 65 g each with shell)
- 60 g coarse sugar
- 50 g cake flour, freshly sifted

Method :
1. Prepare all the ingredients and preheat the Oven to 180C
2. Line a 28 X 28 cm baking pan with parchment paper or an 8 inches round pan for a round shape
3. Prepare a pot with simmering water
4. In a clean stainless bowl, whisk the egg  and add in the sugar. continue whisking by placing the stainless bowl on top of the simmering water that have been prepared before. Wish until the the eggs mixture is warm.
5. One the eggs mixture is warm, put the pot with simmering water away. Using a mixer, beat on high speed for about 5-6 minutes, or until ribbon stage. Lower the mixer speed and continue beating  for another 1 minute.
6. Fold in the sifted flour, fold for not more then 10 folds.
7. pour into the prepared baking pan, bake for 10-12 minutes, depend on your oven.
It need only 8 minutes in an fan on oven.
8 . cool down the baked sponge cake on the cooling rack.