Preheat the oven to 400°F (200°C).

In a saucepan, combine water and butter. Bring to a boil.

Add flour and salt all at once, stirring vigorously until the mixture forms a ball and pulls away from the sides.

Remove from heat and let cool slightly. Beat in eggs one at a time until smooth and glossy.

Transfer the dough to a piping bag and pipe small mounds onto a baking sheet.

Bake for 20-25 minutes until golden and puffed. Let cool completely.

In a bowl, whisk together egg yolks, sugar, lemon juice, lemon zest, and cornstarch.

In a saucepan, heat the mixture over medium heat, stirring constantly until thickened.

Remove from heat and let cool. Whip the heavy cream until stiff peaks form and fold into the lemon mixture.

Cut a small hole in the bottom of each choux pastry and fill with lemon cream using a piping bag.

Serve immediately or refrigerate until ready to serve.