• Preheat the oven to 425°F and line a baking sheet with parchment paper or a silicone baking mat.
• In a large saucepan, combine water, butter, and salt. Place over medium heat and cook, stirring occasionally, until the butter has fully melted and the mixture reaches a boil.
• Take the pan off the heat, then add all of the flour at once. Using a sturdy spoon or a stiff spatula, stir the mixture vigorously until well combined.
• Place the saucepan back on medium heat and stir continuously for about one to two minutes. The mixture should become smooth and start to steam. At this point, the batter will appear quite thick and have a shiny texture.
• Remove the pan from the heat and set it aside to cool for 5 to 10 minutes, stirring occasionally. The dough needs to cool down to between 125°F to 135°F so it doesn’t cook the eggs when you add them. If you don’t have a thermometer, guess the temperature with your finger…it should feel hot but you should be able to hold your finger in it for a few seconds.
• Once it reaches 125°F to 135°F, beat the eggs in (either by hand or with an electric mixer). Wait until each egg is completely incorporated before adding the next one. After you add each egg, the pastry will look like it splits apart but it will eventually come together if you keep beating it. Once all the eggs are incorporated, scrape down the bowl and beat it for 5 to 10 more seconds. The batter should look smooth and glossy and it should hang from the beaters or a spatula in a V shape.

  If the batter is too stiff, whisk an egg in a separate bowl. Then, gradually incorporate the beaten egg into the dough, adding just a couple teaspoons at a time. Continue to beat the mixture until it reaches a smooth consistency. You'll know it's just right when the dough forms a distinct V shape as it falls from the spatula.
• At this point, you can use the pastry right away, or cover it and store it in the fridge for up to 3 days. You can store it in a piping bag or in a bowl with plastic wrap pressed directly on top of the dough so it doesn’t form a skin.

Making Cream Puffs and Eclairs

• Fit a pastry bag with a #6 round tip or cut the end of a pastry bag making a ½ inch cut. Spoon the pastry dough into the bag.
• Holding the piping bag straight up and down, pipe small mounds (about the size of a tablespoon) onto the baking sheet to make profiteroles or cream puffs. Pipe 3 to 4-inch strips if you are making eclairs. Space them about 1-½ inches apart.
• Bake for 15 minutes to 20 minutes for small profiteroles and up to 35 minutes for larger eclairs.
• Keep an eye on them through the oven window and don’t open the door until they turn golden brown. When they turn golden brown, you can open the door and check them. They should feel firm and hold their shape when you poke them with your finger. If they feel soft and sink when you poke them, let them bake a little longer.
• Remove them from the oven and quickly poke a small hole in the bottom of each pastry to let the steam out. Place them back on the baking tray and return them to the oven.
• Turn the oven off and prop the door open with the handle of a wooden spoon. Leave them in the oven for 30 minutes with the door cracked. This will allow them to dry out and get crispy and have the right texture to hold up to the pastry cream.