Place the water, milk, butter, sugar and salt in a saucepan and bring to a boil.
(For crispier puffs, you may use only water for your choux instead of water and milk)
Remove from heat; add all the flour into the butter mixture at once, stirring continuously with a wooden spoon until the mixture forms a 'dough'.
Place the saucepan over high heat and cook, stirring continuously, until the 'smooth dough' leaves the sides of the pan.
Remove from the heat and cool for 5 minutes. Mix in the eggs, one at a time, stirring to incorporate well after each addition with a wooden spoon.
Alternatively, it is a good idea to use the electric mixer. When you've added eggs, the pastry should take on a glossy sheen and have a soft, almost dropping consistency. The texture should be formed into smooth paste that just falls from the spoon but still holds its shape.
Fill pastry into a piping bag attached with a round or rosette nozzle. Pipe into round/rosette, 5cm (2in) apart on the parchment-lined baking trays.
Bake in preheated oven at 200 degrees Celcius and bake for 25 minutes or until golden brown.
Leave the puffs in the oven with the door open after baking to dry them out further for crispier puffs.
Remove the puffs from the oven and transfer to wire rack to cool before garnishing.