This is a basic Choux Pastry recipe

8 fluid ounces water
1/4 pound butter
1 cup flour
4 eggs
1/2 teaspoon salt
1 tablespoon sugar (optional)
1/2 teaspoon vanilla extract (optional)
  1. Preheat oven to 375°F.

  2. Place salt, water, sugar (if using) and butter in a saucepan and heat over medium heat, stirring occasionally. When the water is starting to boil (butter should be melted at this point), add the flour in one go (do this with the saucepan away from the stove/heat) and vigorously mix the flour in, so that it absorbs all of the water (use a wooden spoon or spatula to do this). When the flour has absorbed the water and it's forming a dough, return the pan to the stove (medium heat).

  3. Cook the dough for 2 - 5 minutes while you mix and move it around in the pan until you get a dough that pulls away from the sides of the pan, forms oil droplets on the bottom of the pan, and when you stick a spoon in the dough, it stays upright.

  4. Transfer the dough to a bowl, and let it cool down slightly for a few minutes. Add the vanilla extract (if using), and then with a hand-held mixer (or whisk), mix the dough while adding the eggs one at a time, mixing well after each addition. Make sure the eggs are lightly beaten so that you can stop adding eggs immediately, when you reach the right consistency (i.e. a dough with a glossy sheen with pipeable consistency. You may or may not use up all the eggs, please see the post for details).

  5. Prepare a baking tray with parchment paper and mist the surface with water (either using a mister or lightly sprinkle water with your hands - this is an optional step).

  6. Pipe the desired shape on to the baking sheet - either using a piping bag or spoon it on to the tray, using a teaspoon. Then with a damp finger, flatten the apex and any points.

  7. Bake in preheated oven for 30 - 40 minutes in the center of the oven, or until the choux pastry shells puff up and are golden brown on top. Do not open the oven door, at least until you have reached the 25 minute mark. Importantly, baking time depends on the size of your pastry shell. If you prefer a drier shell, bake for a couple of minutes longer.

  8. During the last 5 - 10 minutes of baking, prick each shell with a skewer or toothpick and let them dry out in the oven while baking. 

  9. Remove from the oven, and let the choux pastry cases cool completely in a draft-free area. Preferably in a place that is not cold. (Letting them cool in an open but turned off oven is even better, but not necessary).  

  10. Fill with a sweet or savory filling and serve immediately. Or you can store cooled choux pastry shells in an air-tight container for up to one day. To store them for longer, keep them in the freezer in an air-tight container.