Place the water and all the other ingredients up to and including the orange zest in a pan, bring to the boil and then reduce the heat. Add the flour all at once, stir with a wooden spoon for approx. 2 mins. until a smooth dough is formed which separates from the base of the pan. Remove the pan from the heat. Using the dough hook on a hand mixer, gradually stir in the eggs; the dough should be soft but not runny. Transfer the mixture into a piping bag with a round nozzle (approx. 14 mm in diameter). Pipe approx. 40 walnut-sized blobs onto a baking tray lined with baking paper, ensuring they are well spaced out.
Approx. 20 mins. in the centre of a fan/convection oven preheated to 180°C. Do not open the oven during baking! Then switch the oven off and leave to dry out with the door ajar for approx. 15 mins., remove from the oven, allow to cool on a rack.
Orange caramel filling
Boil the sugar and water in a wide pan without stirring. Reduce the heat and simmer, swirling the pan occasionally until a brown caramel has formed. Remove the pan from the heat, add the orange zest and juice along with the liqueur, reduce to a syrupy consistency. Remove the pan from the heat, leave to cool. Set 1/3 of the caramel to one side. Beat the cream until stiff, stir in the caramel. Spoon the filling into a piping bag with a smooth nozzle (approx. 6 mm in diameter). Using a wooden skewer, make a small hole in the lower half of each profiterole. Fill the profiteroles.
Gently heat the reserved caramel in a small pan, drizzle over the profiteroles.