Combine the milk, water, salt, sugar and butter in a saucepan and bring to a boil.
When it starts to boil, remove from heat and add the flour, all at once. Mix well with a spatula then place back on heat.
Cook for 2 minutes until a thin layer of dough sticks to the bottom of the pan.
Remove from heat and transfer into a clean bowl.
Allow to cool down for 10 minutes then start adding the eggs, little by little, mixing well after each addition.
When you've added almost the entire amount of eggs, add 1 teaspoon at a time as a little goes a long way. The dough is ready when it looks smooth, shiny and it slowly falls off the spatula or spoon, forming a thin peak as it falls.
Place in a pastry bag fitted with a round pastry tip.
Pipe small dollops of dough on a baking tray lined with baking paper or a silicone mat.
Remove the craquelin from the freezer and cut out small discs using cookie cutters. The discs should be about the same size as the choux dollops. Place the frozen dough over each choux. If the craquelin gets difficult to work with, place back in the freezer for a few minutes.
Bake in the preheated oven at 170C for 35-45 minutes or until slightly golden brown and crisp.
Allow to cool down in the pan.