In a pot over medium heat, add butter, onion, celery, bell pepper, and garlic. Saute the vegetables for about 5 minutes, and then add the seasonings. Stir in the rice and toss well to coat.
Once the grains are lightly golden, stir in the chicken broth. Cover and let simmer to cook for about 15-20 minutes. Once cooked and all the liquid has absorbed, fluff with a fork.
Rub the shrimp with Cajun seasoning, salt, and pepper. Heat olive oil in a pan on medium heat. Add shrimp and cook for 2-3 minutes, just until seared but not fully cooked. Remove from pan and set aside.
Add garlic to the pan, sauté for a minute, and then stir in the butter. Pour the white wine and lemon juice and allow to slightly thicken.
Turn off the heat and toss the shrimp and parsley in the sauce. Serve over the rice.