Preheat your oven to 400°F (200°C).
In a saucepan, combine water, butter, and salt; bring to a boil.
Remove from heat and quickly stir in flour until the mixture forms a ball.
Allow the dough to cool for a few minutes.
Add eggs, one at a time, mixing thoroughly after each addition.
Transfer the dough to a piping bag fitted with a large round tip.
Pipe 4-inch long strips onto a baking sheet lined with parchment paper.
Bake for 25-30 minutes until golden brown and puffed up.
Let the eclairs cool completely on a wire rack.
Whip the heavy cream with sugar and vanilla until stiff peaks form.
Fill the cooled eclairs with the whipped cream using a piping bag.
Dip the tops in melted chocolate or fondant to finish.