In a large heavy pot over medium heat, melt the butter until foaming.
Whisk in the flour and cook, stirring constantly, until the mixture is blonde in color and slightly thickened, about 5 to 6 minutes.
Add the chopped onion, green bell pepper, celery, and minced garlic; cook until the vegetables are softened and lightly browned, about 5 to 6 minutes.
Stir in the diced tomatoes with their juice, shrimp stock (or chicken broth), bay leaves, salt, and cayenne pepper; bring to a boil.
Reduce heat and simmer uncovered for 30 minutes to meld the flavors and thicken the sauce.
Add the peeled and deveined shrimp and cook until the shrimp turn pink and are just cooked through, about 3 to 4 minutes.
Remove and discard the bay leaves, stir in the minced parsley, and serve the shrimp creole hot over cooked rice.
