Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a medium saucepan, combine water, butter, sugar, and salt. Bring to a boil over medium heat.
Remove from heat and add the flour all at once. Stir vigorously until the mixture forms a ball and pulls away from the sides of the pan.
Let the mixture cool for 5 minutes. Add the eggs one at a time, beating well after each addition until smooth.
Transfer the dough to a piping bag fitted with a large round tip. Pipe small mounds onto the prepared baking sheet.
Bake for 20-25 minutes or until golden brown. Let cool completely.
For the cream filling, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
Cut the cooled puffs in half and fill with the whipped cream. Serve immediately.