In a large pan, melt the butter and cook the salt pork or streaky bacon until crisp, without letting the butter discolour or burn. Use a draining spoon to remove the pork or bacon from the pan. Add the garlic, onion and celery to the butter in the pan and cook for 3-4 minutes until they begin to soften. Again, do not let the butter burn as this will spoil the flavour of the chowder.
In a small bowl, blend the flour with a little of the milk until smooth. Add the blended flour mixture and the remainder of the milk to the vegetables, stirring. Add the shellfish, cooking liquid, potatoes, thyme and bay leaves. Bring to the boil, stirring all the time. Reduce the heat and add half of the parsley, half of the coriander, the Tabasco and Worcestershire sauce.
Simmer gently for 6-7 minutes until the potatoes are cooked. Stir in the cockles and mussels and heat through. Then stir in the cream and heat without boiling. Add seasoning to taste and ladle into warmed bowls.
Sprinkle the cooked salt pork or bacon over the top, garnish with the remainder of the parsley and coriander, and serve with crusty bread. If preferred this soup can also be made with chicken and bacon instead of the seafood variety.
Preparation time approximately 30 minutes.