Spongy Japanese Cheesecake

Step 1
Preheat oven to 325 degrees F (165 degrees C). Lightly grease an 8-inch round cake pan and line with parchment paper.

Step 2
Place cream cheese in a bowl with milk; soak for 20 minutes.

Step 3
Heat cream cheese with milk and butter in the top of a double boiler over simmering water, stirring frequently, until melted and smooth, about 5 minutes. Remove from heat and cool completely, at least 15 minutes.

Step 4
Sift cake flour and cornstarch together into a bowl. Sift again into the cream cheese mixture; mix well. Add egg yolks and lemon juice and mix well.

Step 5
Beat egg whites, cream of tartar, and salt together in a separate bowl using an electric mixer until foamy; add sugar, 2 tablespoons at a time, beating well after each addition. Continue beating on high speed until soft peaks form.

Step 6
Fold cream cheese mixture into egg white mixture until well mixed; pour into the prepared pan. Place pan inside a larger baking dish and fill the baking dish with water until it reaches halfway up the sides of the cake pan.

Step 7
Bake in the preheated oven until cheesecake is set and golden brown on top, about 1 hour 10 minutes. Turn off oven and leave cake in oven with door ajar for 1 hour. Transfer to a wire rack to cool completely.