Preheat you're oven to 160°C ( 320°F ) with a large baking pan filled halfway with water or boil water in a pot just before the baking and add it to the larger baking pan.
Shift the all-purpose flour, salt, and cornstarch and set aside
Separate egg yolks and whites keep at room temperature
Grease 8 inch by 3-inch high cake pan with pan release or line bottom and sides with parchment paper.
In a medium-size saucepan add the cream cheese, butter, and milk.
Stove Method - Heat on low until just until melted and well combined stirring occasionally with a spatula or whisk, the mixture will be thick and creamy.
Double Boiler Method - You can also use a double boiler for this process.
Add water to a pot and bring to a boil then add the bowl with cream cheese ingredients onto the boiling pot and melt stirring frequently.
Remove from heat and cool mixture to lukewarm.
Microwave Method - A quicker method to melt all three ingredients (cream cheese, butter, milk) is by microwaving them at 20-second intervals and stirring between until creamy consistency. Cool mixture for a few minutes.
Prepare the batter - Add the sifted flour to the cooled cream cheese mixture and mix by hand using a whisk or spatula until well batter is well combined and smooth.
You can also use a hand mixer or a planetary mixer with the paddle attachment and mix on medium speed for about 2 minutes.
Add in the 6 egg yolks and 1 teaspoon of lemon extract and continue to mix until batter is creamy and smooth and well combined for about 2 minutes. Set Aside.
In a separate clean and dry mixing bowl add the egg whites and mix on medium speed using a planetary mixer with the whisk attached or beat using a hand mixer.
Once egg whites start to froth add the cream of tartar and continue mixing for 10 seconds, then slowly add in the 100 grams of sugar and continue to mix until meringue is fluffy, glossy, and is a medium peak consistency.
Add dollops of meringue (whipped egg whites) in separate stages to cake mixture, cut and fold in gently using a spatula scraping the sides of the bowl until batter is creamy and well combined.
Pour batter into 8 inches greased cake pan and bang onto the counter twice to break down air bubbles.
Carefully place the baking pan onto preheated water pan or place the pan onto a larger pan and pour in boiling water and place into the middle rack in the oven.
Baking - Bake for 20 minutes at 160°C ( 320°F ) then drop temperate to 140°C ( 285°F) and continue to bake for 55-60 minutes or until the top is golden brown.
Remove from oven and let cool in the cake for 10 minutes
Slowly invert onto a plate then invert onto another plate and cool for an additional 20 minutes before serving.