Melt butter in a large pot or Dutch oven over medium heat.

Whisk in flour to create a medium-brown roux.

Add onions, celery, bell pepper, bay leaves, salt, cayenne pepper, and white pepper.

Cook, stirring, until vegetables are soft (7-8 minutes).

Add garlic and thyme, stir for about a minute.

Add most of the water and sherry, stir well.

Bring the mixture to a boil, add remaining water if needed, ensuring it coats a spoon.

Add Rotel tomatoes, parsley, green onions, and Creole seasoning.

Simmer for about 6 minutes until the mixture thickens.

Add shrimp and crawfish and simmer until seafood is cooked, shrimp curled and pink.

Discard bay leaves and serve over steamed rice.

Garnish with parsley and green onions.