Prepare the equipment and ingredients. Prepare the baking pans, electric mixer and kitchen tools such as a fine mesh strainer, spatula, whisk, and mixing bowls. Weigh and measure all the ingredients accurately before you start.
Make the cheesecake batter. Boil water and pour into a medium-sized bowl. You can also use a double boiler and bring the water to a low simmer. Add the cream cheese, butter, and milk to another medium-sized bowl that is a bit bigger than the other bowl. Then place this bowl over the bowl with hot water or over slowly simmering water, if using a double boiler. Mix until cream cheese and butter are melted and smooth. Remove from hot water, and sift the flour with salt over the warm cream cheese mixture. Mix until well incorporated, then add egg yolks, lemon zest, and pure vanilla extract. Mix until well blended. Pass through a fine-mesh strainer and set aside.
Make the meringue. In another medium-sized bowl or a bowl of a stand mixer, add the egg whites and lemon juice. Whisk on high speed while gradually adding sugar. Whisk until medium-stiff peaks.
Folding the meringue into the cake batter. Using a rubber spatula, scoop about a cup at a time of meringue and fold into the cake batter. Scraping from the side of the bowl down to the bottom of the bowl and folding motion until no more streaks of cake batter are visible.
Pour and divide the cake batter into the prepared greased pans, about 3/4 full. Swirl the cake batter with a skewer or chopstick to even out the surface. Then tap to remove some air pockets.
Water bath the cake. Place them on a sheet pan and pour hot water into the sheet pan to cook in a "bain-marie"(water bath).
Oven temperature. Slide in the middle rack of the preheated oven to 300°F.
Baking time for the Japanese Cheesecake. Baking time may vary, depending on the sizes and volume of cake batter in the baking pans. For baking pans sizes I used in this recipe: 4"× 2" star or flower shape baking pans and 5"×2" round baking pans.First Bake for 15 minutes. The second bake for 10 minutes with the door oven open, about an inch (use oven mitts) gap. The third bake, rotate for even browning, then continue baking for another 10 minutes. The total baking time is 35 minutes. Cooling the cake. Turn off the oven heat and leave the cakes inside with the oven door about halfway open, to gradually cool the cake for 10 minutes. From the oven, while still warm, remove the cake immediately from the baking pans to avoid steaming and cake shrinking or collapsing. Transfer on a cake server to cool completely. Serving the cake. Best to serve chilled. Serve and dust with powdered sugar then top with whipped cream and fresh fruit if desired.