Preheat your oven to 400°F (200°C) and grease a large baking dish with a little olive oil.
In a large mixing bowl, combine the halved baby potatoes, sliced smoked sausage, olive oil, garlic powder, paprika, and black pepper. Toss everything until the potatoes and sausage are evenly coated.
Transfer the potato and sausage mixture into the greased baking dish, spreading it out in an even layer.
Bake in the preheated oven for 30 minutes, stirring halfway through to ensure even cooking.
After 30 minutes, remove the baking dish from the oven and drizzle the ranch dressing over the top. Gently toss to combine.
Sprinkle the shredded cheddar cheese over the potato and sausage mixture, returning it to the oven.
Bake for an additional 10-15 minutes, or until the cheese is melted and bubbly. The potatoes should be fork-tender at this point.
Once done, remove from the oven and let it cool for a few minutes. Garnish with chopped green onions before serving.