Preheat your oven to 400°F and line a baking sheet with parchment paper.

In a medium saucepan, combine the water and butter over medium heat until the butter is melted and the mixture comes to a boil.

Remove from heat and add the flour and salt all at once, stirring vigorously until a ball forms.

Allow the dough to cool for about 5 minutes, then add the eggs one at a time, mixing well after each addition.

Stir in the vanilla extract until the dough is smooth and glossy.

Drop tablespoon-sized mounds of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 20-25 minutes until puffed and golden brown, then let cool completely on a wire rack.

While cooling, whip the heavy cream until soft peaks form, then gradually add powdered sugar, lemon juice, lemon zest, and vanilla extract until stiff peaks form.

Once pastries are cool, cut a small slit in each and fill with lemon cream using a piping bag.

Serve immediately or refrigerate until ready to serve.