Preheat the oven to 350F (180C) with ventilation on and line a baking pan with parchment paper.
In a saucepan, bring the milk, water, butter, sugar and salt to a simmer.
Once the butter is melted, reduce the heat to low and add the flour all at once. Stir vigorously with a wooden spoon. The dough needs to come together as a smooth ball and the bottom of the pan will have a skim of dough stuck to it.
Remove from the heat and add the eggs, one at a time, mixing with a hand mixer after each one. Mix until you get a soft paste that will hold its shape.
Use a piping bag fitted with a big round or star tip and gently pipe the dough into 2 3/4 inches (7 cm) logs and leave a little space between each log.
Bake them for about 25-30 mins. They should be puffy and start to turn golden-brown. Remove from the oven and let them cool before filling.