• Preheat the oven to 350℉

Instructions for the cake batter:

• Separate the egg yolks from the egg whites.
• Place the egg yolks in a bowl and add the sugar and vanilla to the egg yolks and mix well. The batter will turn a light yellow color when all is incorporated.
• Add in water, vanilla, oil and give the mixture another stir then set it aside.
• After sifting the flour, salt and baking powder add the dry ingredients in thirds to the wet ingredients. Set the cake batter aside.

Instructions for incorporating the egg whites:

• Place the egg whites in a separate bowl and beat on medium speed until bubbles form.
• Add cream of tartar and continue mixing on high until stiff peaks form.

Instructions for adding egg whites to cake batter:

• Using a silicone spatula, add ⅓ of the whipped egg whites into the cake batter.
• Gently incorporate the egg whites into the batter by folding the egg whites into the batter. Don't stir too much because it will deflate the egg whites leading to a flat baked cake.
• Continue incorporating until all the egg whites are gone.

Instructions for baking the Vietnamese sponge cake:

• Gently pour the batter into a well greased 8" cake pan. Lightly tap the cake pan onto a soft surface to remove any bubbles from the batter.
• Place the cake pan in a slightly larger pan. Place both pans inside the preheated oven then fill the outer pan with hot water about 2 inches deep.
• Bake the cake in the water bath for 50 minutes at 350^oF. After 50 minutes, turn the temperature down to 275^oF and bake for another 10 minutes.
• Insert a toothpick in the middle of the cake to make sure it is baked through.
• Turn the oven off and with the oven door slightly open, leave the cake in there to slowly cool. I left the cake to cool in the oven for 60 minutes.
• Remove the cake from the oven & serve & enjoy.