Preheat the oven at 170 degree celcius (upper heating coil) with a bigger pan (enough to fit 2 pcs 6 pan, filled with 1 cm height of water)
Line two 6 pans with parchment paper and also the side of the pan. Separate the egg yolks and egg whites
To make the paste: heat the butter in low fire, until small bubbles appear. Mix in the flour with spatula l/whisk until well combined. Off the fire, mix in condensed milk.
Mix this condensed milk mixture to the egg yolk mixture (6 egg yolks + 1 whole egg). Whisk until the paste turns smooth.
To make the egg whites meringue: beat the white eggs with electric mixer, in medium speed until frothy. Add in 1/4 tsp of cream tartar and sugar 1/3 part at a time. Continue beating in medium high mixer until reach stiff peak form.
With a spatula, fold in the meringue into the egg yolk mixture in 3-4 batches.
Pour the batter into the prepared cake pan. Lightly bang the pan a few times to remove any trapped air bubbles in the batter.
Carefully put the pan into bigger pan with water inside the oven at the lowest rack.
Steam-bake the batter in a preheated oven set at 170 degree Celsius with only the upper heating coil for 40 minutes at lower rack of the oven. After 40 minutes the cakes will look like this.
After 40 minutes, reduce the oven temperature to 150 degree Celsius with both upper and lower heating, for another 20 to 30 minutes. If the cakes brown too fast, cover with aluminium foil. Test with skewer to see if it's done. The skewer should come out clean.
Remove the cake with pan from the oven and drop the pan with the cake from a height of about 5 cm for about three times. This is to prevent the cake from over shrinking during the cooling period
Let the cakes cool down in the cooling rack until the cakes slightly shrink from the sides of the pans. Then take it out from the pan and let it cool down completely.
Ready to serve. Enjoy!
