Combine milk, water, butter and a good pinch of salt in a saucepan and heat over medium heat until just boiling.
Remove immediately from the heat, add all the cake flour at once, mix well and use a spatula to combine.
Return the saucepan to low heat and beat until the mixture is smooth and a flour film forms on the bottom of the pan (video 2:11). Remove the saucepan from the heat and set aside until cooled slightly.
Transfer the mixture into a mixing bowl.
Whisk eggs (3-4) and measure them to 56g (yep, you have to measure the mixture).
Preheat oven at 160°C.
Add whisked eggs into the flour mixture gradually, beat with the spatula after each addition until well combined and the mixture thickens and becomes smooth before adding more.
You may need to add more or less, the mixture has to be in a smooth, shiny, falls heavily and thick consistency (video 2:32).
Pipe out choux pastry into about 3-4cm (dia).
Use a round cookie mould to cut the cookie dough sheet (this is the craquelin disc), the size should match with the chop pastry (about 3-4 cm in diameter).
Place the disc on top of the choux pastry.
12. Bake for 20-25 mins at 160°C
Rest until fully cooled down