Recipe source: here kindly translated by Kat Kat (FB Group friend)
3 eggs yolks – I used grade B eggs which is about 60g
1 whole egg
35g corn oil
50g plain flour
Pinch of salt
50g condensed milk
3 eggs whites
1/8 tsp cream of tartar or 1/2 tsp lemon juice
Line the base of an 6″ round pan. Do not grease the sides.
1. Put oil in a saucepan and heat on low fire until just simmering. If you have a thermometer it should read 70C. Remove and immediately add the flour and stir with a whisk until smooth.
2. Lightly whisk the condensed milk, salt, egg yolks and 1 whole egg to together and add into the flour batter to mix well.
3. Beat the egg whites until foamy then add cream of tartar (or lemon juice) then gradually add sugar to beat until firm peaks form.
4. Add 1/3 of the meringue into the yolk batter and using the hand whisk to mix until combined. Add the next 1/3 portion and whisk again. Finally, add the last portion, whisk briefly before switching to spatula to scoop the batter from bottom and fold up on to the batter to make sure all are combined and no more yolk batter can be seen.
5. Pour into prepared pan and bake in water bath at 160C for 15 minutes before lowering to 145C for another hour or until the cake bounces back when you lightly press the top.
6. Remove from oven and leave it for a couple of minutes before unmoulding. You can invert it like you would a chiffon cake to cool completely before unmoulding if you wish.
7. Cool completely before you proceed to frost the cake if you wish.