Add 4 tbsp butter to a medium saucepan over medium heat. Once melted, add diced garlic, cajun seasoning, and onion powder. Cook for 2-3 minutes, until fragrant, then pour in the chicken broth and water. Bring to a boil, then slowly pour in the grits, stirring constantly. Reduce heat to low, cover with a lid, and cook for 20-25 minutes, stirring occasionally, until the grits are tender. Add in black pepper, cheddar cheese, remaining butter, and heavy cream. Stir until the cheese is melted, then taste for salt and adjust as needed. Remove from heat and cover with lid. Set aside.
Season shrimp with 2 tsp of cajun seasoning in a large bowl. Toss to ensure shrimp are coated, then sprinkle a drizzle of olive oil into a large pan over medium heat. Warm the pan for about 3-4 minutes, then add shrimp. Cook for 3-4 minutes (about 2 mins per side), until pink and slightly curled. Remove from the pan and set aside.
Add andouille sausage to the pan and cook until browned, about 5-7 minutes, then add in the onion, bell pepper, and celery. Cook for 5 minutes, then add in the garlic and remaining 1 tsp of cajun seasoning. Continue to cook for 2 minutes. Pour in diced tomatoes, chicken broth, heavy cream, Worcestershire sauce. Mix together and reduce heat to medium low. Cook for 10-15 minutes, until the sauce is slightly thickened.
Add in the lemon juice, hot sauce, and return shrimp back to the pan. Stir everything together and remove from heat.
Spoon grits into serving bowls (if the grits have stiffened, add a little milk to then and stir together to loosen them back up). Top with the shrimp and spoon the sauce/gravy with the veggies on top. Top with fresh parsley and parmesan and enjoy!
Notes
Don't overcook the shrimp – Sauté shrimp in a hot pan for 2–3 minutes per side until just opaque and tender. Overcooked shrimp turn rubbery.Serve immediately – Shrimp can overcook if left sitting in a hot pan, so plate everything as soon as it's done for the best texture.Pat the shrimp dry before seasoning to help them sear properly. This helps them brown nicely!Cook grits to your liking - if you prefer looser grits, cut cooking time by a few minutes or add more liquid. For thicker grits, cook for an additional 5 minutes.Not all cajun seasonings are created equally - there are some seasoning with no salt and some with lots of salt! As you'll see, I don't add any salt in the ingredients this list because I don't want your dish to be too salty. Taste as you go and add (or omit) kosher salt as per your personal preference.