Preheat your oven to 400°F (200°C) and prepare your baking sheet by lining it with parchment paper to prevent sticking.

Boil together the water and butter in a medium saucepan over medium heat until bubbling.

Mix in the flour and salt, stirring until a cohesive ball forms. Return the saucepan to the heat for an additional 1-2 minutes.

Cool the dough in a mixing bowl for a few minutes. Gradually add the eggs one by one, mixing thoroughly after each addition.

Pipe the choux pastry into small mounds (1.5 inches in diameter) on the prepared baking sheet.

Bake for 20-25 minutes, until puffs are beautifully puffed and golden brown.

Cool completely on a wire rack.

Heat your milk in a saucepan over medium heat until it simmers gently.

Whisk together the sugar, cornstarch, and egg yolks in a bowl until perfectly smooth.

Combine the hot milk with the egg mixture, pouring slowly while whisking continuously.

Return the mixture to the saucepan and cook over medium heat, stirring constantly until it thickens (about 2-3 minutes).

Remove from heat and stir in the vanilla extract and butter until creamy and smooth.

Slice open each cooled puff using a small knife to create a slit.

Fill a piping bag with the cooled vanilla custard and gently pipe it into each puff.

Dust the filled cream puffs generously with powdered sugar just before serving.

Drizzle with chocolate or caramel sauce, if desired.

Serve your delightful cream puffs chilled or at room temperature.