01 - Melt the butter with the olive oil in a large pot over medium heat. Add the onion, celery, and carrot and sauté until softened, about 6 to 8 minutes.
02 - Stir in the garlic and cook for 1 minute. Add the tomato paste, Old Bay seasoning, and paprika; cook for another 2 minutes, stirring frequently to develop color and fragrance.
03 - Pour in the sherry or white wine, scraping up any browned bits from the bottom of the pot. Let simmer for 1 to 2 minutes until slightly reduced.
04 - Add the seafood stock and bay leaf. Bring to a simmer, cover, and cook for 15 minutes to build depth of flavor.
05 - Remove and discard the bay leaf. Using an immersion blender, purée the mixture until completely smooth. Alternatively, transfer to a standard blender in batches and return to the pot.
06 - Stir in the whole milk and heavy cream. Return to a gentle simmer without letting it come to a full boil to prevent curdling.
07 - Add the lump crab meat and chopped shrimp. Simmer gently for 6 to 8 minutes until the shrimp are pink and cooked through.
08 - Season to taste with salt and pepper. Ladle into bowls, garnish with chopped parsley, and serve with lemon wedges on the side if desired.