Start off by sweating the Vegetables in a little olive oil and Butter. Add the Rice and cook for one minute. Pour in the sherry wine and Reduce. Meanwhile in another pot steam the mussels and clams with some garlic and white wine. Once the Shells are open, remove from the pot and leave to cool in a bowl. Add the remaining juices together with the fish Stock in the other pot. Reduce Gently for twenty minutes. Meanwhile remove the mussel and Clam Meat from it shell. Blitz the Chowder and pass trough a fine sieve. Put it back on the heat, skim and add the fresh cream. Bring to the boil and simmer for a further ten minutes. In a separate non stick pan sear the scallops. Place the prawns mussels, clams and the scallops in serving bowls. Pour in the hot chowder ,add chopped chives and serve.