Preheat oven to 210C. Prepare Pastry bag
Place the water and cubed butter in small saucepan. Bring to a boil to melt butter then add flour and beat vigorously with a wooden spoon until the dough is smooth and pulls away from the pan sides. Remove from heat and let cool-- this is important because if not cooled it will cook the eggs in the next step.
Once butter flour mixture is cooled, add 1 egg at a time until dough is smooth and glossy. This takes a couple minutes with lots of beating so be patience and mix in the eggs well.
Place the smooth dough in the pastry bag then pipe to desired shape on baking paper lined trays.
Bake in hot oven for 20-25 mins. They will puff up but sometimes seem to take longer than you think. So keep a watch , its better to slightly overcook so they don't collapse when they cool.
Once cooked, let the puffs cool completely, 1-2 hours then fill with whipped cream and topped with melted chocolate.