Preheat your oven to 400°F. While it heats, prepare all your vegetables: dice the red and green peppers into 1-inch pieces, dice the celery, seed and mince the jalapeno, and cut the chicken thighs into 1-inch chunks. Pat the shrimp dry with paper towels—this is crucial for getting them to brown properly rather than steam. In a small bowl, combine all the dried spices (paprika, smoked paprika, salt, pepper, garlic powder, onion powder, cayenne, oregano, and thyme) to create a unified seasoning blend that you'll use throughout the cooking process.

Spread the chicken chunks, sliced andouille sausage, red pepper, green pepper, celery, and jalapeno across a large sheet pan. Drizzle with 2 1/2 tablespoons melted butter and sprinkle with 1 1/2 tablespoons of the Cajun seasoning (or about half your spice blend), then toss everything together to coat evenly. Bake for 12 minutes until the chicken is partially cooked and the sausage begins to brown. I like to use Cajun seasoning as my main flavor base here because it brings everything together beautifully without needing additional liquid.

Remove the pan from the oven and stir in the cauliflower rice and diced tomatoes, distributing them evenly throughout. Nestle the patted-dry shrimp on top of the mixture—don't stir them in yet, as you want them to make direct contact with the pan for better browning. Drizzle the remaining 2 1/2 tablespoons melted butter over everything and sprinkle with the remaining 1 1/2 tablespoons Cajun seasoning. I find that keeping the shrimp on top initially prevents them from getting buried and ensures they cook evenly.

Return the sheet pan to the oven and bake for 10 minutes until the shrimp turn opaque and the chicken is fully cooked through. Switch your oven to broil and place the pan on the upper rack for 2 to 4 minutes, watching carefully to lightly char the tops of the shrimp and vegetables without burning them. This broiling step adds depth and a subtle smoky char that elevates the dish.

Remove the pan from the oven and let it rest for 1-2 minutes. Gently fold everything together to combine, then taste and adjust seasoning if needed. Divide among plates and garnish generously with fresh chopped parsley.