Castella Cake Creme Caramel Pudding

This cute, delicious, and delicate pudding is a combination of Castella cake and crème caramel pudding.

Combine sugar, water, and lemon juice in a saucepan, and cook over medium heat until the sugar has dissolved.
Let it boil, do not stir. When the sugar syrup is just beginning to turn into amber color, turn down the heat to low. Tilt the saucepan to spread the caramel and cook for 2 minutes, then remove it from the heat.
Carefully pour the caramel into pudding cups and let it cool down.

Separate one egg yolk from the white and reserve the egg white for later.
In a big bowl, add 1 egg yolk, add 3 eggs, and sugar, whisk together until well combined.
Pour milk and keep whisking until all ingredients are mixed well.
Strain pudding through a fine-mesh strainer into a jug.
Remove the foam from the top with a spoon.
Pour the pudding mixture into the cups over the caramel.

In a big bowl, put an egg white, one egg, and sugar, beat with an electric hand mixer on medium-low speed for around 2 minutes or until foamy, then increase the speed and beat for around 4 minutes or until a stiff peak and a pale yellow color is achived.
Sift the flour into the bowl and fold with a spatula to incorporate.
Scoop the castella batter on top of the pudding mixture.
Place cups in a baking tray and pour hot water halfway into the tray.
Bake in a preheated oven at 160ºC for 28 minutes or until the top has golden brown color.
Remove the baking tray from the oven, take the cups out of the water bath and let them cool down to room temperature, and then refrigerate for 2 hours.