Preheat the oven to 200°C.
Bring the pan with the milk, water, butter and salt to the boil.
Remove the pan from the heat and stir in the flour. Put back on the heat and let the mixture cook for 1 to 2 minutes while stirring. Remove the pan from the heat again and stir in the eggs 1 at a time, until they have been absorbed and a nice smooth and flexible batter has been created.
Fill a piping bag with an 8 mm nozzle with the batter and pipe sausage sized moulds of 10-12 cm on a baking paper-lined and lightly greased floured baking sheet. Bake in the oven for 20-25 minutes. Leave them to cool on a grid.