In a large Dutch oven or heavy-bottomed saucepan over medium heat, combine butter, oil, and flour until smooth.
Cook on medium heat, stirring continuously, for 10-12 minutes, and you’ve achieved the desired color. Don’t walk away from the stove during this process because it burns fast.
Add the onion, green bell pepper, and celery, and cook for 8-10 minutes, stirring frequently.
Then add the garlic, thyme, and bay leaf, continuing to stir for another 2 minutes.
Toss in the chopped tomatoes, Worcestershire sauce, smoked paprika, and Creole seasoning, and cook for 5 more minutes.
Gradually pour in about 2 cups of shrimp stock (see notes), bring to a boil, and let it simmer for a few minutes. Add the shrimp, and simmer for 5 more minutes. Or you may season the shrimp with Creole seasoning and sauté for about 5 minutes. Then throw it in at the last minute. You've got two options here – both work.
Adjust the thickness of the soup and flavor with more shrimp broth or water, hot sauce, and salt.
Stir in green onions and chopped parsley. Serve shrimp etouffee with the blackened catfish and cooked rice.