Preheat oven to 350F (180C). Line a baking sheet with parchment paper.
Sift the flour. In a saucepan bring the milk, water, sugar, salt and butter to a boil.
Remove from heat and add flour all at once and incorporate mixing energetically with a wooden spoon until homogenous.
Return the saucepan over low heat and while stirring cook for 1-2 minutes more to pull out the moisture from the batter and until it pulls away from the sides of the pan. You will see some of the dough sticks to the bottom of the pan.
Transfer batter to a large bowl and allow to cool slightly. Add the eggs one at a time, carefully incorporating each into the batter using the wooden spoon or even a stand mixer. It will result in a smooth, homogenous batter which still holds its shape.
Fit a pastry bag with a 1/3 inch (9mm) plain tip and pipe the dough on the prepared baking sheet into small circles, up to 1 inch (2 cm) diameter.
Bake for 25-30 minutes until browned and puffed.
Prick each with a skewer to release steam and allow to cool on a wire rack. When cooled enough poke a hole in the base of each profiterole using a small plain tip.