Separate 5 beautiful eggs. Place the egg yolks in a bowl, and the egg whites in a mixer bowl.
Place the butter, cream cheese and ¼ cup of fine sugar into a pot over low-heat. Allow the ingredients to melt, and mix together into a beautifully smooth batter mixture.
Remove the pot from heat, and add the egg yolks into the batter mixture. Mix well, but gently.
Add the cornstarch and flour. Once again, mix well. Clumps should disappear.
Add milk and optionally vanilla extract or other flavors of your choice.
Mix well. The batter should be smooth and liquid-y. You won’t have to strain this mixture.
Set aside the batter as you beat the egg whites into stiff peaks.
Pre-heat oven to 330F. Prepare a bain-marie by putting water in a deep rectangular baking pan or dish. Place into the oven.
Prepare baking pans— with these ingredients, you can bake one 8-inch cake or two 6-inch cakes. Line the bottoms of the baking pans with circular parchment paper, and the inside sides with rectangular strips of parchment paper.
Once you achieve stiff peaks, place some beaten egg white into the batter and mix together.
Repeat the above step two more times.
Pour the batter into the rest of the egg whites and mix together using folding techniques. Avoid over-mixing or under-mixing.
Pour the well-incorporated batter into the baking pan(s).
Bake bain-marie style for 25 minutes at 330F. Adjust the temperature if necessary.
If the cake hasn't risen after 25 minutes, keep it at the same temperature and give it time to rise, or raise the temperature by 10 degrees.
Once the cake rises, crack open the oven door slightly for 10 seconds and lower the temperature to 245-265F for an additional 45 minutes.
Allow the cake to rest in the oven for about 10 minutes after baking.
Remove the cake from the oven carefully using oven mitts.
Place a sheet of parchment paper over the cake, then flip the cake upside down onto a plate.
Remove the wet parchment paper and replace the bottom parchment paper.
Place another plate on top of the cake and flip again carefully.
Serve the cake while still warm, or chill in the fridge, though it will lose its fluffiness when chilled.