1Add potatoes and chopped onion to the bottom of a slow cooker.
2Drizzle with olive oil and season with salt, pepper, and Cajun seasoning.
3Toss to coat evenly.
4Layer the sliced smoked sausage and green beans on top.
5Sprinkle with onion soup mix and garlic powder.
6Place pieces of butter evenly over the top.
7Cover and cook on Low until potatoes are tender and everything is well flavored, 6 to 7 hours, stirring a few times throughout the process and just before serving.