Preheat the oven to 400°F (200°C) and grease a large rimmed sheet pan with non-stick spray or parchment paper.
In a large mixing bowl, combine the cubed potatoes and sliced sausage.
Drizzle olive oil over the potatoes and sausage, then sprinkle with the ranch seasoning, garlic powder, onion powder, and black pepper.
Toss the ingredients thoroughly until the potatoes are evenly coated in oil and spices.
Spread the mixture in a single layer across the prepared sheet pan.
Bake for 35 to 40 minutes, or until the potatoes are fork-tender and golden brown, flipping halfway through.
Remove the pan from the oven and sprinkle the shredded cheddar cheese evenly over the potato and sausage mixture.
Return the pan to the oven for 3 to 5 minutes until the cheese is fully melted and bubbling.
Garnish with fresh parsley and serve immediately.