Preheat oven to 400°F (200°C).
In a saucepan, combine butter, water, and salt. Bring to a boil.
Remove from heat, add flour, and stir until a dough forms.
Add eggs one at a time, mixing well after each addition.
Transfer dough to a piping bag and pipe onto a baking sheet.
Bake for 20-25 minutes or until golden brown.
For the filling, whip the heavy cream, sugar, and vanilla extract until stiff peaks form.
For the topping, heat the chocolate chips and heavy cream until smooth.
Once the pastries are cool, fill with cream and top with chocolate.