Line a cake pan with parchment paper, ensuring it extends slightly over the edges.

Cut a parchment paper circle for the bottom of the pan.

Wrap the cream cheese in plastic wrap and flatten it.

Microwave in short intervals to soften the cream cheese, avoiding overheating.

Cream the softened cream cheese in a bowl using a whisk.

Melt the butter and gradually add it to the cream cheese, mixing well after each addition.

In a separate bowl, combine egg yolks and sifted cornstarch, mixing until smooth.

Slightly soften the sour cream in the microwave.

Add the softened sour cream to the egg yolk mixture and combine thoroughly.

Incorporate the milk into the sour cream mixture, mixing well.

Gradually pour the egg yolk mixture into the cream cheese mixture, combining evenly.

Strain the batter through a strainer 2-3 times to ensure a smooth consistency.

Scrape any batter from the whisk and bowl edges, incorporating it into the mixture.

In a clean bowl, whip egg whites with granulated sugar until soft peaks form.

Preheat the oven to 170C (338F).

Ensure the whipped egg whites are thick and flow slowly back into the bowl when scooped.

Gently fold 1/3 of the whipped egg whites into the cream cheese batter using cutting motions.

Add the remaining egg whites, gently folding with a rubber spatula to maintain air bubbles.

The batter should leave marks that quickly disappear on the surface after being drizzled.

Pour the batter into the prepared cake pan and gently shake to even the surface.

Place the cake pan on a baking tray.

Pour water into the baking tray to reach about 2cm up the sides of the cake pan (double boiler setup).

Cover the bottom of the cake pan with foil or a stainless steel plate to prevent water leakage.

Place the baking tray with the cake pan in the preheated oven.

Lower the oven temperature to 150C (302F) and bake for 45-50 minutes, or until golden brown and elastic.

Leave the cheesecake in the pan to cool completely.

Remove the cooled cheesecake from the pan using the parchment paper.

Cover the cheesecake with plastic wrap and refrigerate for 24 hours to allow the flavors to meld.

Serve the chilled cheesecake.

For leftovers, individually wrap slices in plastic wrap, place in an airtight container, and freeze.

Thaw frozen slices in the microwave or serve frozen for a cream cheese ice cream-like experience.