Pour the milk into a large bowl. Place the bowl over simmering water on the stove top. Be sure that the bottom of the bowl does not touch the simmering water.
Add cream cheese and stir it occasionally until it’s completely melted and the mixture is smooth. Stir in the butter and stir until it melts into the cream cheese. Remove from heat and let it cool for a few minutes. You don’t want to add the egg yolks while it’s hot otherwise the eggs will cook. Add the egg yolks and stir to combine.
In a medium bowl, combine the cake flour and corn flour. Sift in the flours into the cream cheese mixture in batches stirring between before adding more. There shouldn’t be any lumps in the batter. Stir in the lemon zest.
Place egg whites in a large clean bowl. (Note: Make sure there’s no oil or water in the bowl at all.) Beat the egg whites for 3 minutes, add the cream of tartar and beat again. Pour the sugar in the egg whites and beat until the egg whites hold very stiff peaks.
Fold-in the egg whites into the cream cheese mixture gently with a rubber spatula just until all ingredients are incorporated. Do not stir or beat.
Pour the mixture into the two baking pans. Place the pans into another larger baking tray. Add hot water in the tray up to half way. Bake for 50 to 60 minutes or until an inserted toothpick or cake tester comes out clean.
Turn off the oven. Leave the oven door ajar for 10 minutes. Remove the pans from the oven and remove the cakes from the pans. Cool the cakes completely on a wire rack. Chill in a fridge for about 3 hours before slicing and serving.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.