Preheat oven to 400-degrees.
Bring the water, butter, and salt to a simmer in a saucepan over medium heat.
Add the flour and stir vigorously until the mixture comes together to form a dough. Allow it to cool slightly (approximately 10 minutes).
Add the eggs, one at a time, beating extremely well with a wooden spoon after each addition. Continue until all four eggs have been incorporated, and the choux paste is smooth and glossy.
Spoon (or pipe) 12 mounds of choux paste, evenly spaced, onto a baking sheet that has been lined with parchment paper or a silicone baking mat.
Tap down any dough spikes or points with a finger that has been dampened with water.
Bake the profiteroles in a preheated oven for 30-35 minutes or until they're puffed and golden.
Remove the profiteroles from the oven and immediately pierce each one with a paring knife or skewer to release any internal steam.
Allow them to cool completely on a wire rack.
Using a serrated knife, gently cut the tops off each eclair, reserving the tops for later.
Gently pull out any internal dough (if needed) so each puff is now a shell and ready to be filled. Set aside.
Add the heavy cream to a very cold bowl that has been chilled at least 20 minutes.
Whip or whisk on high speed until the cream becomes thick and soft peaks form.
Whisk in the confectioner's sugar and vanilla extract to combine.
Gently fold in the orange curd and orange zest (optional) until completely combined.
Spoon the orange curd whipped cream into the prepared profiterole shells, and gently set the reserved tops in place on each eclair.
Sprinkle the cream puffs with additional confectioners sugar and chill until ready to serve.