125g plain flour
Bring water and butter to boil in a small pot
When the butter has melted add the flour and pinch of salt
Mix over the heat until the mixture becomes smooth and glossy, coming away from the edges of the pan.
Transfer to a food mixer, cool slightly.
Then start adding the eggs one by one - mixing well after each one.
When the dough is smooth, glossy and holding its shape it's ready for piping.