Combine the milk, 125ml water, the butter, salt and sugar in a saucepan and set over a low heat. Bring the boil and immediately take the pan off the heat. Shower in the flour and beat the mixture with a wooden spoon until spoon.
Return the pan to a medium heat for about 1 minute, stirring constantly, to dry out the paste. Tip it into the bowl.
Add the eggs one by one, beating with the wooden spoon. Once they are all incorporated into the mixture, it should be smooth and shiny and thick enough to pipe. The choux paste is now ready to use. (If you are not using it immediately brush the surface with eggwash to prevent a crust forming)
Pipe small mounds on a baking sheet line greaseproof paper in staggered rows, using a bag fitted with a 1cm nozzle. Brush with eggwash and lightly mark the tops with the back of a spoon. Bake at 200ºC/Gas 6 fir 15-20 minutes until crisp, but still soft inside. Cool on a window sill.