In a medium saucepan, combine the water, butter, sugar and salt and boil over medium high heat.
Once the mixture comes to a boil, reduce heat to medium. Then, add all of the flour, and quickly stir to combine.
Stir the mixture constantly for about 2-3 minutes until the mixture begins to pull away from the sides of your saucepan to form a ball and leaves a thin film or coating on the bottom of your pan. Allow to cool.
Place the cooled dough ball into a mixing bowl. With a hand or stand mixer, begin mixing in your eggs one at a time on medium speed. Make sure each egg is well combined into the mixture before adding the next egg. Allow the mixture to cool for a few minutes.
Once all of your eggs have been added in, mix in your cinnamon. You now have your Choux Pastry dough.
Pour your dough onto your piping bag, fitted with the large plain round tip.
Preheat your oven to 350 F degrees, and line a baking sheet with parchment paper.
Pipe 2-inch circles of dough on the lined baking sheet. Keep them about 1.5-inches apart. If your puffs have little peaks, dab a clean finger in a little water to soften the peaks.
Lightly brush each puff with egg wash, and bake in the oven at 350 F for 12 minutes.
Raise the oven temp to 425 F degrees, and bake for another 10-13 minutes. You’re looking for a raised puff, golden brown in color, and hollow in the middle. Allow the puffs to cool completely to room temperature before filling.