Preheat your oven to 320°F (160°C). Line a cupcake tin with paper liners or grease it lightly to prevent sticking.

In a mixing bowl, combine the softened cream cheese and 1/4 cup of granulated sugar. Beat with an electric mixer until smooth and creamy, ensuring there are no lumps.

Add the milk, vanilla extract, and lemon juice to the cream cheese mixture. Mix until well combined.

In a separate bowl, whisk the egg yolks until they are pale and fluffy. Gradually add the egg yolks to the cream cheese mixture, mixing well after each addition.

Sift the cake flour into the cream cheese mixture and fold it in gently with a rubber spatula until just combined. Be careful not to overmix, as this can affect the texture.

In a clean mixing bowl, add the egg whites and cream of tartar. Using an electric mixer, beat the egg whites on medium speed until they become frothy.

Gradually add the remaining 1/4 cup of granulated sugar while continuing to beat the egg whites. Increase the speed to high and whip until stiff peaks form. This step is crucial for achieving the light, airy texture of the cupcakes.

Gently fold the whipped egg whites into the cream cheese batter in three additions. Start by adding one-third of the egg whites to lighten the batter, then fold in the remaining egg whites carefully to maintain the airiness.

Spoon the batter into the prepared cupcake tin, filling each liner about 2/3 full to allow for rising.

Bake in the preheated oven for 20-25 minutes, or until the tops are golden and a toothpick inserted into the center comes out clean. The cupcakes should be puffed and slightly jiggly in the center.

Once baked, turn off the oven and leave the cupcakes inside for 10 minutes with the door slightly ajar. This helps prevent them from collapsing due to sudden temperature changes.

Remove the cupcakes from the oven and allow them to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.

Once cooled, you can serve the cupcakes plain or top them with whipped cream, a dusting of powdered sugar, and fresh berries for an elegant touch.