Preheat Oven:
Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
Boil Liquid:
In a medium saucepan over medium heat, combine water, butter, salt, and sugar (if using). Bring to a rolling boil.
Add Flour:
Remove from heat and immediately stir in all the flour at once. Return to medium heat, stirring constantly until the mixture forms a ball and pulls away from the sides of the pan (about 1–2 minutes).
Cool Slightly:
Transfer dough to a mixing bowl and let it cool for 3–5 minutes.
Incorporate Eggs:
Beat in eggs one at a time, mixing well after each addition. The dough should be smooth, shiny, and pipeable, but thick enough to hold its shape.
Pipe or Spoon:
Transfer dough to a piping bag fitted with a large round or star tip. Pipe desired shapes onto prepared baking sheet, leaving space between each.
Bake:
Bake at 425°F (220°C) for 10 minutes, then reduce temperature to 375°F (190°C) and bake for another 15–20 minutes until golden brown and puffed. Avoid opening the oven door during baking.
Cool:
Remove from oven and let cool completely on a wire rack before filling.