½ cup water
½ cup flour, sifted
Boil water and butter. Remove from heat and add sifted flour and salt. Return to heat and beat continuously with a wooden spoon until a ball forms and leaves the sides of the saucepan. Cool slightly and beat in each egg thoroughly one at a time. The mixture is now ready and can be easily applied using a piping bag. You could also use a strong plastic bag with one corner cut off.
Bake immediately at 180 degrees celcius in a pre-heated oven for about 40-45 minutes. Choux pastry must be thorougly baked. if the sides of the walls are moist, when removed from the oven, steam will condense back into water and the still-wet walls will recoil. This will cause the choux pastry to collapse/ and flattened itself.
You can check if the choux pastry shells are properly baked by removing a shell from the oven and tear it apart to see if the entire choux is dry. Only remove the entire batch when they are dry.