In a large Dutch oven or heavy-bottomed saucepan, combine melted butter, oil, and flour until smooth.
Cook on medium heat, stirring continuously, for about 10-12 minutes or until you've achieved the desired color. Don't walk away during this process because it might burn.
Add the onion, green pepper, and celery, and cook for 8-10 minutes, stirring frequently.
Then add garlic, thyme, and bay leaf—continue stirring for another 2 minutes.
Next, toss in about a cup of chopped tomatoes, Worcestershire sauce, paprika, and Creole seasoning, and let it cook for 5 minutes.
Gradually pour in about 2 cups of shrimp stock, bring to a boil, and let it simmer. Add the shrimp and simmer for 5 more minutes. Or season the shrimp with Creole seasoning, sauté for about 5 minutes, and then throw them in at the last minute. You've got two options here – both work.
Adjust the soup's thickness and flavor with more shrimp broth or water, hot sauce, and salt.
Stir in the green onions and chopped parsley, and serve over hot cooked rice.