Scampi turban with Champagne and caviar sauce

Instructions

1. For the fish stock, place all the ingredients into a large pot, cover with cold water and bring to the boil. Reduce the heat to low and simmer gently, skimming the top regularly for 30 minutes. Strain, discard the solids, then set the stock aside.
   
2. For the sauce, place a saucepan over medium heat. When hot, add the butter, shallots, thyme and pepper. Stir to combine well, then add the Champagne and the fish stock and simmer until reduced by half. Add the cream and simmer until reduced by half again. Remove from the heat and set aside until serving.
   
3. Place the 8 nicest and largest scampi tails on a clean kitchen cloth. Pass the remaining scampi through a fine drum sieve and place into a large bowl. Add the egg whites and whisk until well combined. Cover and refrigerate until cold.
   
4. Bring a saucepan of salted water to the boil. Add the olive oil and spaghetti and cook for 9 minutes or until al dente. Drain the spaghetti, then run under cold water to stop the cooking process. Return to the pan, drizzle with a little extra oil and toss to combine well.
   
5. Grease 4 savarin moulds with the softened butter. Working with one mould at a time, coil in the spaghetti until the mould is completely lined. Refrigerate the lined moulds for 30 minutes or until set. Spread 1 small spoonful of mousse over the base of each mould, then line with 2 scampi tails each. Cover the scampi with the remaining mousse, making sure there are no holes. Cover in plastic wrap and place in a steamer basket over boiling water. Cover and steam for 7 minutes.
   
6. To serve, remove turbans from the moulds and invert onto serving plates. Gently reheat the sauce over medium heat. When warm, add the caviar and chives and spoon sauce over the turban. Finely grate the lemon zest over the top and serve immediately.