Preheat Oven: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Make the Dough: In a medium saucepan, combine the water, unsalted butter, salt, and sugar. Warm over medium heat until the butter melts and the mixture reaches a soft boil.

Add the Flour: Reduce the heat to low and add the flour all at once. Stir vigorously with a wooden spoon for about 2–3 minutes until the dough pulls away from the sides of the pan and forms a smooth ball.

Cool Slightly: Remove the saucepan from heat and let the dough cool for about 5 minutes.

Incorporate the Eggs: Add the eggs one at a time, beating well after each addition. The dough should be smooth, thick, and glossy. If desired, incorporate the vanilla extract when adding the last egg.

Pipe or Scoop the Dough: Transfer the dough to a piping bag fitted with a large round tip, or use a spoon to form mounds on the prepared baking sheet, spacing them about 2 inches apart.

Bake: Bake for 20–25 minutes or until the choux pastries are puffed and golden brown. Refrain from opening the oven door while baking, as this may cause the pastries to collapse.

Cool and Fill: Allow the pastries to cool completely before slicing and filling them with whipped cream, custard, or pastry cream. Garnish with fresh berries if desired.