1. Melt the butter in a large pot over medium heat. Add the onion and celery, then cook until softened and fragrant.

2. Stir in the garlic and cook for a brief moment until aromatic.

3. Add the tomato paste and cook, stirring, until it darkens slightly and blends into the vegetables.

4. Sprinkle in the flour and stir well to form a smooth base.

5. Slowly pour in the seafood stock while whisking to keep the mixture smooth and lump-free.

6. Stir in the paprika, Cajun seasoning, salt, black pepper, and Worcestershire sauce, then let the soup simmer gently.

7. Reduce the heat and stir in the heavy cream until the broth becomes smooth and creamy.

8. Add the shrimp and cook until just pink and tender.

9. Fold in the crab meat and let it warm through gently.

10. Stir in the parsley and lemon juice, then taste and adjust seasoning if needed.

11. Serve hot with crusty bread or crackers.