In a small saucepan, gently heat Milk, Cream Cheese, and Butter on low heat, and stir until Cheese has melted into the Milk. Do not allow to mixture to come to the simmer. Allow mixture to cool down.
Whisk the Egg Yolks into cooled milk mixture. Sift Flour and Cornstarch over top, and whisk to combine.
In a stand mixer, whisk Egg Whites and Cream of Tartar until frothy and begin to hold shape. Then slowly stream in Sugar, and continue whisking until soft peaks form.
Take 1/4 of whisked Eggs Whites, and fold into Egg Yolk mixture. Then add remaining Egg Whites in ¼ increments, and gently fold until hardly any streaks of white can be seen.
Cover the bottom of an 8 inch springform pan with three layers of aluminum foil. Spray the bottom and sides of pan lightly with cooking spray. Line the base and sides with parchment paper.
Gently pour batter into lined pan, and tap to remove any air bubbles. Place pan in a large deep dish, and fill the dish two inches of the way up the side with boiling water.
Place in a 400 degree oven and bake for 25 minutes to brown top, then lower oven to 325 degrees and bake for an additional 30 minutes. Then switch off oven and allow cake to sit for an additional 20 minutes.
Remove from oven and allow to cool slightly for two to three minutes, or until you can safely touch the pan without burning your fingers. Release the springs of the pan, and lift up the outer circle. Peel away parchment paper off the sides. Cut into slices and enjoy!