Easy Shrimp & Sausage Gumbo

In a large, deep skillet over medium-low heat, melt butter, then add flour. Cook, stirring constantly, until dark caramel colored, 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 broth 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 shrimp. Once shrimp is pink and cooked through, taste and adjust seasonings. Stir in green onions, reserving some for garnish. Serve spooned on top of white rice.