Add water and butter to a saucepan until the water simmer and the butter melts.
Add all the flour and stir vigorously until the mixture comes together into a heavy dough.
Allow the choux paste dough to cool slightly. Approximately 5 minutes.
Add the eggs, one by one, stirring vigorously after each addition. A little elbow grease is required, or you can do this process with a hand mixer or stand mixer.
After the addition of the final egg, the choux paste dough will be smooth and glossy.
Drop approximately 2 tablespoons of the choux paste dough onto a parchment or Silpat lined baking sheets. Leaving space in between each eclair.
Tap down any spiky points with a wet finger if needed.
Bake the eclair shells in a preheated 400-degree oven for approximately 30 - 35 minutes.
Remove the eclairs from the oven and immediately poke a steam hole in the side of each eclair to let the steam out so they won't deflate as they cool.
Allow the eclair shells to cool completely before using a serrated knife to gently slice tops off each eclair shell.
Gently pull out any of the doughy interiors that may still remain on the inside of each eclair shell to make room for the filling.
Set the shells and tops aside while you prepare the filling.