1/4 cup (4 oz) unsalted butter, cut in small pieces
1 cup water
1 cup sifted flour
1/4 teaspoon salt
Combine butter and water in saucepan. Cook over medium heat until butter is melted and mixture is boiling. Turn heat to very low. Add flour mixed with salt all at once. Stir vigorously until a ball forms and does not stick to the pan. Stir over heat another minute or two to slightly dry out. Remove from heat and transfer to a clean bowl. Allow to cool 1 minute.
Add eggs, one at a time, beating hard after each addition. The final egg should beaten with a fork and added gradually to ensure the right consistency. Batter should be just stiff enough to stand at a peak when a spoon is withdrawn or if a finger is run through it, the channel fills in slowly. Sometimes it’s necessary to add slightly less or even one more egg depending on the dryness of the flour and the temperature of the room.