Easy Prawn & Sausage Gumbo

In a large, deep pan over medium-low heat, melt butter, then add flour. Cook, stirring constantly, until dark caramel coloured, about 10 minutes. Add onions, peppers, and celery, and stir until softened, about 5 minutes more. Stir in garlic and sausage, then season with Cajun seasoning, salt, and pepper. Stir in bay leaf, diced tomatoes, and chicken stock and bring to a boil. Reduce heat to low and simmer until thickened, stirring occasionally, about 1 hour. In the last 10 minutes of cooking, add prawns. Once prawn is pink and cooked through, taste and adjust seasonings. Stir in spring onions, reserving some for garnish. Serve spooned on top of white rice.