Preheat oven to 425 degrees.
In a large saucepan, combine water, butter, sugar, and salt.
Cook over high heat until butter is melted and liquid comes to a rolling boil.
Remove from heat and add flour all at once. Using a wooden spoon, mix in flour until no lumps remain. Return saucepan to stovetop and continue to cook until a dough forms; about 1 - 2 minutes. Remove from heat and continue to stir allowing the dough to cool slightly. Using a hand held mixer, add eggs one at a time being sure the egg is fully incorporated before adding the next. Once all the eggs are added, continue to mix until a smooth shiny paste forms. To test for doneness, lift the beaters up and the paste should drop back into the bowl forming a "V" shape off the beater.
Line an baking sheet with parchment. Drop by heaping tablespoonfuls spacing them 3 inches apart. Bake for 25 minutes until, puffed and lightly golden brown. Turn off oven, using a wooden spoon prop oven door open to allow the puffs to cool down slowly. This will prevent them from deflating.
Once the puffs are cooled, split and fill with your favorite custard, ice cream, mousse...the possibilities are endless.