Preheat the oven to 425 degrees and line a baking sheet with parchment paper, you can use a silicone baking mat I prefer parchment.
Heat the water, salt, sugar, and butter in a saucepan, stirring, until the butter is melted. Remove from heat and add all the flour at once.
Stir quickly until the mixture is smooth and pulls away from the sides of the pan.
Briskly beat in the eggs, one at a time, until smooth and shiny.
Using two spoons, scoop up a mound of dough with one spoon about the size of a walnut and then scrape it off with the other spoon onto the baking sheet. Or you can use a pastry bag, I like the number 807.
Place the mounds evenly-spaced apart on the baking sheet.
Brush the top of each mound with some of the egg glaze then sprinkle the sugar crystals over the top, don’t be shy on this part. Use a lot!
Bake the puffs for about 30 minutes, or until puffed and well-browned.