Bring the water, butter and salt to a boil in a pot. Once it is boiling, add the flour all at once, stir and move around until the paste unsticks from the edges of the pot.
Set aside and allow to cool. Add the eggs, one by one, stirring until obtaining a smooth paste.
Preheat the oven to 400°F.
Cover an oven tray with parchment paper and divide the dough into portions using a spoon or a piping bag.
Bake the profiteroles for about 30 minutes until they have risen and are brown.
Mince the chives and mix with cream cheese, mustard and dill.
Remove the profiteroles from the oven and allow to cool on a baking rack.
Cut them into halves and fill with cream cheese, a slice of smoked salmon and a blackberry.