How to Make It
Preheat oven to 425°F. Place sausage and onion on a large rimmed baking sheet. Drizzle with 1 tablespoon of the oil and 1/2 teaspoon of the Creole seasoning; toss to coat. Bake in preheated oven until onions are softened and sausage blisters, about 8 minutes.
Meanwhile, toss together shrimp, 1 teaspoon of the Creole seasoning, and remaining 1 tablespoon oil. Arrange in an even layer over the sausage mixture. Return to oven, and bake until shrimp is pink, about 4 more minutes.
Stir together rice, salsa, and remaining 1/2 teaspoon Creole seasoning. Spoon over and around shrimp and sausage, and return to oven; bake until rice is warmed through and tender, about 6 minutes. Sprinkle with scallions, and serve hot.