For rice, melt butter over medium heat in a large saucepan. Add the celery, onion, garlic, and bell pepper. Saute for about 5 minutes, or until soft. Don’t let it brown. Stir in the Cajun seasoning.
Add the rice and stir until rice is slightly toasted. Add the chicken stock, bring to a boil, then reduce heat and cover. Cook for 10-15 minutes, until liquid is absorbed. Fluff with a fork, then cover, set aside and keep warm
For the shrimp, melt 2 tablespoons of the butter over medium-high heat in a large heavy skillet. Sprinkle the shrimp with the Cajun seasoning.
Add the shrimp and cook until golden brown on each side; about 5 minutes for large shrimp. Add the garlic and cook only until garlic is aromatic; about 30 seconds.
Remove the pan from the heat and add the lemon juice and zest, tossing to coat. Add the remaining 1 tablespoon of the butter, tossing the shrimp in the melting butter.
Serve immediately over the rice.
Top with the chopped parsley if using.
To make your own Cajun seasoning, follow link in the first heading.