Preheat oven to 350 degrees F (176 degrees C).
Into a deep, oven-proof skillet, add Olive Oil (2 1/2 tablespoon). Dice Celery (3 stalk), then add it to the pan.
Dice Cubanelle Pepper (1), then add it to the pan.
Dice Orange Bell Pepper (1), then add it to the pan.
Dice Onion (1), then add it to the pan.
Stir to combine. Cook for 2-3 minutes.
Slice Italian Sausage (0.5 pound) at an angle, then add to the pan.
Stir to combine. Cook for 1-2 minutes.
Add Garlic (2 clove), Long Grain White Rice (2 cup), and additional Olive Oil (3 tablespoon). Stir to combine. Cook over high heat for 2 minutes.
Add Creole Seasoning (2 tablespoon). Mix well.
Add Beef Stock (3 3/4 cup) and Diced Tomatoes (1 can). Stir. Remove pan from the heat.
Bake for 30 minutes in the preheated oven.
Into a mixing bowl, add Large Shrimp (1 pound), remaining Olive Oil (1/2 tablespoon), and remaining Creole Seasoning (1/2 tablespoon). Mix well to coat. Cover and let sit for 15 minutes.
Transfer shrimp to a sheet pan lined with parchment paper. Bake along with the rice for the last 6 minutes the rice is in the oven.
Arrange the shrimp around the edges of the rice pan. Garnish with Scallion (to taste). Season with Kosher Salt (1/2 teaspoon) and Coarse Black Pepper (1/2 teaspoon).