Okra and Shrimp Gumbo

I brought this recipe back from New Orleans.

1/2 cup flour
1/2 cup salted butter
1 1/2 large yellow onions diced
4 stalks diced celery
2 green bell peppers diced
1 bunch green onions chopped
1 clove garlic minced
8 oz.diced tomatoes drained
3 lb.okra sliced
1 lb.60/70 Louisina shrimp
3 qt.shrimp or chicken stock
3 tbsp.Worcestershire
1/12 tbsp.kosher salt
1 tsp. black pepper
1/2 tsp cayenne
1 tsp granular Zatarain's Crab Boil or Old Bay Seasonings
2 bay leaves

In an oven-safe dish, cook okra covered at 350 degrees for one hour,
stirring twice. In an 8 qt.pot combine flour and butter. Cook over
medium heat, constantly stirring and scraping the bottom of the pot
until the roux is caramel colored. Add diced onions, celery,
peppers, green onions, and garlic, and stir to combine the roux.
Cook until the onions are transluccent. Incorporate tomatoes,
smothered okra, and stock to roux and seasoning mixture. Bring
to a simmer. Add seasonings and cook for 30 minutes. Add seafood
and cook on low for 30 minutes partially covered, stirring occasionally.