Preheat your oven to 400°F (200°C). Lightly grease a large baking dish or sheet with cooking spray.
In a large mixing bowl, toss the quartered potatoes with olive oil, garlic powder, onion powder, ranch seasoning, salt, and pepper.
Spread the seasoned potatoes evenly onto the baking dish. Bake for 25–30 minutes, flipping halfway through, until golden and tender.
Remove the baking dish from the oven and add the sliced smoked sausage. Toss everything together and return to the oven for another 10–12 minutes.
Sprinkle shredded cheddar cheese evenly over the top and bake for an additional 5 minutes or until the cheese is melted and bubbly.
Remove from oven, garnish with chopped green onions, and serve hot.