Add in the butter and cook for about 10-12 minutes until a light golden brown. Be sure to stir around a few times to prevent burning.
Whisk in the flour until smooth and cook again for about 8 minutes on low. It should look like a slightly loose peanut butter when its ready.
Add in the bell peppers, celery and onion. Stir and coat the veggies with the roux. Cook for another 10-15 minutes, until the veggies are softened.Stir in the garlic and thyme and cook for a minute, until the garlic is fragrant.
Add in the tomato paste, Worcestershire sauce, creole seasoning and broth. Simmer on low for 30-40 minutes until slightly thickened. Stir occasionally.Stir in the shrimp, shut the heat and put the lid on. Allow to cook for about 5-8 minutes or until cooked through. Stir in a Tbsp of butter right at the end.
Serve over rice and garnish with sliced scallion and fresh diced tomato.