1.Preheat oven to hot. 220°C (200°C fan forced). Lightly grease two oven trays.
2.Combine butter with the water in small saucepan, bring to a boil. Add flour, beat with wooden spoon over heat until mixture comes away from base and side of saucepan and forms a smooth ball.
3.Transfer mixture to small bowl, beat in egg with electric mixer until mixture becomes glossy.
4.Spoon mixture into piping bag fitted with 1cm plain tube, proceed with éclair, profiterole or paris-brest recipes.
Choux pastry mixture will come away from side of pan and form a ballNote