Put the water, milk, butter, sugar and salt into a saucepan and bring to the boil. Add the flour and stir with a wooden spoon for at least a minute, until the mixture comes away from the base and sides of the pan.
Pour the mixture into a bowl and leave to cool a little. Beat the eggs and add them slowly to the mixture, stirring continuously. The mixture should be shiny and smooth.
Pre-heat the oven to 220°C (200°C with a fan oven) and line a baking tray with greaseproof paper.
Pour the mixture into an icing pipe with a large, smooth nozzle (or a plastic bag with the corner cut off) and ‘draw’ circles with a diameter of approx. 2.5 cm onto the tray. If they look irregular, smooth the surface with wet fingers.
Bake for 15 minutes (or less if they are getting too dark) then lower the oven temperature to 180°C (160°C with a fan oven) and bake for a further 10-15 minutes. You should be able to take them off the paper without them breaking. Leave to cool on a wire rack.
Whip the cream with the sugar and vanilla.
Open the cooled profiteroles in half and fill with cream.
Sprinkle with a dusting of icing sugar.