In a large cast-iron Dutch oven or similar deep heavy skillet, melt 1/2 cup butter. Whisk in flour. Cook stirring or whisking over low heat until mixture is a caramel-colored paste similar to peanut butter. About 20 minutes.
To the pot add the onion, celery, pepper and onions; stir until coated. Cook over medium heat until the vegetables begin to soften, around 5-8 minutes. Add minced garlic, cooking for 1 minute longer.
Next, pour in stock, tomatoes, Worcestershire sauce, Cajun seasoning, salt, pepper, cayenne, bay leaves and thyme. Bring to a boil.
Reduce heat; cover and simmer for 30 minutes, stirring occasionally.
Uncover, discard bay leaf and thyme stems. Add crawfish, lemon juice, green onions and 2 tablespoons parsley. Add a few dashes of hot sauce. Cook uncovered over medium low for 10-15 minutes or just until crawfish is heated through. Whisk in reserved 2 Tbsp butter. Mix well. (Reserve a few green onions for garnishing)
Serve ladled over cooked white rice, with hot sauce and garnished with reserved parsley and green onions.
Please note: If you want to thicken the etouffee further at the end of cooking you can by using tomato paste 1 tablespoon at a time until desired thickness is reached.
**Please Note** Cajun style etouffee wouldn't typically include tomatoes. We love them in this dish and they're included. You can omit them and adapt with extra fish or shrimp stock, if desired.