Preheat your oven to 320°F (160°C). Grease an 8-inch round cake pan and line the bottom with parchment paper.
In a large mixing bowl, beat the softened cream cheese until smooth. Gradually add the granulated sugar, mixing until well combined. Pour in the milk, vegetable oil, and vanilla extract. Mix until smooth and creamy.
In a separate bowl, whisk the egg yolks until light and frothy. Slowly add the egg yolks to the cream cheese mixture, mixing well after each addition.
Sift the all-purpose flour, cornstarch, and salt into the cream cheese mixture. Stir gently until just combined.
In another clean bowl, whip the egg whites with cream of tartar until soft peaks form. Gradually add the remaining sugar while continuing to beat until stiff peaks form.
Gently fold the whipped egg whites into the cream cheese mixture in three additions until no white streaks remain.
Pour the batter into the prepared cake pan. Place the cake pan in a larger baking dish filled with hot water. Bake for 50-60 minutes until the top is golden and a toothpick inserted in the center comes out clean.
Turn off the oven and leave the cheesecake inside for 15 minutes with the door slightly ajar. Remove from the oven and let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.