Step 1

In a saucepan, heat water, salt, and butter. When the mixture boils, add the flour all at once and stir quickly. Keep stirring for five minutes. Leave the mixture to cool a bit and start adding eggs, one by one, mixing until incorporated after each addition.

Step 2

Transfer the mixture into a piping bag and start piping 4x0.5-inch (10x1.25 cm) oblong shapes onto a buttered baking pan, taking care there is a lot of space between each.

Step 3

Bake for 20 to 30 minutes at 350°F/180°C or until they are golden brown. When baked, leave to cool.

Step 4

Mix the cornstarch with a bit of cold milk. Bring the remaining milk to a boil, then stir in the cornstarch and milk mixture. Cook for 10 minutes, stirring constantly. Whisk the eggs, then add the sugar and the thickened milk, and cook in a bain-marie for five minutes. Blend in the salt or butter, then, once cooled, flavor however desired; for example, vanilla, almonds, or lemon.

Step 5

Split the éclairs and fill with cream; top with vanilla or chocolate icing.