Vietnamese Sponge Cake (Banh bong lan )

On the streets of Saigon, Vietnam, a little dessert is made on a cast iron mold with charcoal on top and underneath. It was exciting while waiting for the baker first to prepare the batter and then to finish baking. Sponge cake reminds me of this little cake that I had when I was young. Maybe it is a little different in taste because of the way it is prepared. Either way, I like them both,

Ingredients:
3/4 cup all-purpose flour
1/4 tsp baking powder
1/4 cup milk
1/8 tsp salt
4 eggs separated
3/4 cup sugar
1 tsp vanilla

Directions:
Grease and line with parchment paper a 9 inch diameter round or 9 inch square baking pan. Set aside
Sift floor, baking powder and salt. Set aside.
Separate the egg yolks from the egg white and put in different bowls.
Divide the sugar equally into two portions.
Using an electric mixer, whisk the egg white while adding sugar until stiff.
With the electric mixer, whisk the egg yolks while adding sugar until pale yellow or double in volume. Add flour and vanilla. Mix to combine. Lightly fold egg white mixture into egg yolks mixture. Pour batter in prepared baking pan and bake in preheated oven set at 375° for 30 to 40 minutes.