In a medium saucepan, combine water, butter, and salt. Bring to a boil over medium heat until butter melts.
Reduce heat to medium-low, add flour all at once, and stir vigorously until dough pulls away from the sides of the pan.
Transfer to stand mixer. Beat on medium with paddle attachment for 3 minutes to release steam.
Add eggs one at a time, fully incorporating each before adding the next.
Fold in Pecorino Romano PDO and herbs (if using). Dough should be glossy, smooth, and pipeable.
Transfer pâte à choux to a piping bag fitted with a round tip. Transfer to the fridge to cool slightly.