Heat butter in saucepan; add carrot, celery, bell pepper, parsley, and garlic, saute until onions are tender, about 5 minutes.
Add sherry to the pan and cook off most off the alcohol, deglazing the bottom of the pan as you go.
Pour in broth and add potatoes, and bring to a boil; then reduce heat, cover and simmer for about 12-14 minutes, stirring occasionally, until potatoes start to get tender.
Add tomatoes, bay leaf, paprika, chili powder, celery seed, pepper, thyme and cayenne; cover and simmer another 20 minutes or until mixture begins to thicken.
Stir in shrimp, scallops and crab, and cook until shrimp curl and turn bright pink and scallops turn opaque, and chowder is heated through, about 3 minutes.
Stir in 1/4 cup parsley.
Serve with crusty loaves of Italian or French bread and herb butter, if you desire.
