Preheat oven to 425º F.
Line a rimmed baking sheet with parchment paper and set aside.
Measure out all ingredients and set aside.
Bring the water, milk, butter, salt and sugar to a boil in a medium heavy saucepan.
When butter is melted, reduce the heat to low and stir.
Add the flour to the butter mixture all at once and beat the mixture vigorously with a wooden spoon for 1 minute until it pulls away from the sides of the saucepan and forms a ball of dough.
Transfer the dough to a mixing bowl and let cool for 3-4 minutes, stirring occasionally, until dough is lukewarm.
Add eggs one at a time, beating well after each addition with an electric mixer or a wooden spoon. (It may seem that the mixture is not blending and coming together, but it will. Just keep beating!)
Spoon the warm mixture into a pastry bag fitted with a large ¾-inch round tip. (If you do not have a pastry bag, you can use two spoons to scoop out the mixture and form the pastry or a large freezer bag for piping. (See Gr8 Tip below).
Pipe (or scoop) 18 mounds (about 1 ¼ inches wide and 1 inch high and 1 inch apart) on the baking sheet.
Moisten your finger with water and lightly press down on the swirl at the top of each mound of dough.
Bake the pastries in a 425º F oven for 12 minutes. Lower the heat to 375º F and bake for an additional 10-12 minutes, or until puffed and golden brown (they should sound hollow when tapped on the top and bottom). Keep an eye on them as you don’t want them to burn.
Prick the side of each profiterole with a skewer to allow the steam to escape.
Return to the 375 ℉ oven to dry, propping the oven slightly ajar, for about 2 minutes.
Remove and cool on a sheet of parchment paper on a wire rack.