01 - Preheat oven to 320°F. Line bottom and sides of 8-inch round cake pan with parchment paper. Wrap exterior of pan with aluminum foil to create water-resistant seal.
02 - Set heatproof bowl over pot of simmering water. Combine cream cheese, butter, and milk in bowl. Stir continuously until completely smooth and melted. Remove from heat and allow to cool for 5 minutes.
03 - Sift cake flour, cornstarch, and salt together directly into warm dairy mixture. Whisk vigorously until no lumps remain and mixture is completely uniform.
04 - Add egg yolks, lemon juice, vanilla extract, and lemon zest to batter. Whisk until fully incorporated and smooth. Set aside.
05 - In clean, dry bowl, beat egg whites with electric mixer on medium speed until foamy. Add 5 tablespoons sugar in three portions, continuing to beat until stiff, glossy peaks form and peaks stand straight when beaters are lifted.
06 - Gently fold one-third of meringue into batter using rubber spatula. Add remaining meringue in two additions, folding with light, circular motions until just combined. Do not overmix.
07 - Transfer batter to prepared cake pan. Tap pan firmly on counter three times to release trapped air bubbles. Smooth top with spatula.
08 - Place cake pan inside large roasting pan. Carefully pour hot water into roasting pan until it reaches halfway up sides of cake pan.
09 - Bake for 60 to 70 minutes until cake is golden brown, set in center, and skewer inserted into middle comes out clean.
10 - Turn off oven and leave door slightly ajar. Let cheesecake remain inside for 15 minutes to prevent sudden temperature change and cracking.
11 - Remove from oven. Let cool completely in pan for 1 hour. Unmold and refrigerate for minimum 2 hours before serving.