Peel and devein the shrimp - saving the heads and peelings. Place the peeled shrimp into the refrigerator.
Add the shrimp peelings (and heads) to a large pot. Chop the tops and tails from the green onions, bell peppers, onions and celery and add to the pot with the shrimp peelings. Fill with water (about 11 cups I got). Bring to a boil, cover and simmer for one hour.
While the shrimp stock is cooking you can work on the next steps. Add the butter to a large heavy bottomed skillet. Add medium-high heat.
Add the chopped onions, bell peppers and celery (holy trinity) and cook over a medium heat for about 30 minutes, until nice and soft.
Add the garlic and cook another 2 minutes.
Add the flour and mix into the vegetables, cooking for another 5 minutes.
Strain the shrimp stock and add 3 cups to the skillet, along with the canned tomatoes, Worcestershire sauce, hot sauce, sugar, seasonings and bay leaves. Cover and simmer for 1 hour, stirring every so often so it doesn't stick.
Add the shrimp, parsley and green onions and mix well. Cover and simmer for 15 minutes.
Serve over rice.
Notes
To shorten the cooking time, you could use store-bought seafood stock or even chicken broth and frozen peeled shrimp. You'll need to allow the shrimp to thaw but this will decrease the cooking time. I'm not going to lie though, it won't be as good π