In a large pot with a tight-fitting lid, melt 2 tablespoons of butter over medium heat.
Add the onion and red bell pepper. Cook, stirring occasionally until softened (about 3-4 minutes).
Add the minced garlic to the pot and cook for one more minute.
Stir in the uncooked rice and 1 tablespoon of Cajun seasoning. Make sure the rice is evenly coated with the seasoning and combined with the vegetables.
Pour in the chicken broth and bring the mixture to a boil. Once boiling, reduce the heat to low, cover the pot with a lid, and simmer for 15-20 minutes, or until the rice is tender and the liquid has been absorbed.
Remove the pot from the heat and let it sit, covered, for an additional 5 minutes. This step allows the rice to steam and fluff up. After 5 minutes, use a fork to gently fluff the rice.
While the rice is resting, prepare the shrimp. In a large bowl, combine the shrimp with the remaining tablespoon of Cajun seasoning.
In a large non-stick skillet over high heat, melt the remaining 2 tablespoons of butter.
Once the butter has melted, add the shrimp to the skillet. Spread the shrimp into an even layer and cook for 2-3 minutes on each side. Avoid overcooking to prevent a rubbery texture.
Once the shrimp are cooked, fold them into the rice and vegetable mixture, gently combining everything.
Garnish the dish with chopped fresh parsley and serve with lemon wedges for squeezing.