Heat butter in a large Dutch oven over medium heat.
Place sliced sausage in the pot and cook for 3 minutes. Transfer them to a bowl.
Next, add chopped vegetables, spices (including salt and pepper), and diced tomato to the pot. Cook over medium heat for 2-3 minutes, stirring often.
Add sausage, and stir in the brown rice and chicken broth. Increase heat to high and bring to a heavy simmer for 2 minutes. Reduce heat to low, cover Dutch oven with lid and cook for 30 minutes.
Check rice for tenderness. If it is tender, stir in the shelled shrimp, cover, and cook for 5 more minutes. If not, cook rice for another 5-10 minutes or until it becomes tender, then add the shrimp and cook for an additional 5 minutes. Shrimp should be pink and firm when cooked through.
Taste jambalaya for salt content and adjust accordingly.
Once cooked, remove the pot from the heat. Spoon out your desired amount and garnish with sliced green onion.
Store leftover jambalaya in an airtight container in the refrigerator for up to 3 days after preparation. Reheat well before serving.