To a large skillet or soup pot, melt butter or oil over medium-high heat. Sauté sausage, flipping occasionally, until the edges are golden and caramelize. About 5-ish minutes. Transfer sausage to a plate and keep the rendered fat in the skillet.
Add the onion, bell pepper, and celery to the skillet. Saute until the veggies are soft, 3-4 minutes.
Stir in minced garlic, smoked paprika, Cajun seasoning, salt and pepper. Cook 30–60 seconds until fragrant.
Add can of drained diced tomatoes, and stir to coat in the spices.
Pour in the rice and chicken broth, scraping up any browned bits on the bottom of the pan.
Stir the andouille back into the skillet so it cooks with the rice and flavors the broth.
Bring the mixture to a gentle boil, then reduce the heat to low. Cover with a lid and simmer for 18-20 minutes, or until the rice is tender and the liquid has absorbed.
Fluff the rice with a fork. Serve with a drizzle of Cajun Ranch Sauce, if using.