Pre- heat the oven to 400 degrees.
Bring water and butter too a boil, let it foam up and then remove from heat, and then add the flour, stirring until it forms a ball.
One at a time thoroughly mix in the egg, ( your dough should have a shine to it)
On parchment paper line cookie sheet drop the dough either using a teaspoon or table spoon (depending on what size shell you want), put in the oven and for the first 15 minutes bake at 400, then lower the temp to 350, bake until nice a brown and crisp. ( here again it depends on the size you make) remove from oven and cool.
In a large chilled bowl whip the cream until soft peaks form, then slowly add the powder sugar. The fun part is you have to keep test tasting until you get the sweetness you desire. Mix until stiff peaks form.
Gently cut off the tops of the puffs, remove any dough filaments to create a nice pocket for the whip cream, put the tops back on, and top with chocolate ( I use melted candy bars or powder sugar).