Pour 2 cups of water into a deep saucepan or stewpan, add salt, sugar and butter. Place on medium heat and, stirring constantly, bring the homogeneous mass to a boil.
Pour the sifted flour into a saucepan, mix well to avoid lumps, and remove from heat.
Cool the dough. Add the eggs one by one to the saucepan, stirring each time until smooth, so that the dough is elastic and glossy. It should not be thick.
Transfer the dough into a pastry bag. Place the dough in small circles on a prepared baking sheet lined with parchment. Place the baking sheet with profiteroles in an oven preheated to 180 ℃ and bake for 30 minutes.
When the profiteroles are ready, cut them in half and spread with custard.