Preheat the oven to 400°F and line a large baking sheet with parchment paper or aluminum foil.
In a large bowl, toss the diced potatoes with olive oil until evenly coated. Sprinkle the ranch seasoning mix, garlic powder, onion powder, smoked paprika, salt, and black pepper over the potatoes and toss again to ensure they’re well seasoned.
Spread the potatoes in a single layer on the prepared baking sheet, making sure they’re not crowded. This will help them crisp up evenly.
Bake in the preheated oven for 25 minutes, then use a spatula to flip the potatoes. Return to the oven and bake for an additional 20–25 minutes, or until the potatoes are golden brown and fork-tender.
Remove the baking sheet from the oven and sprinkle the shredded cheddar cheese and Parmesan cheese evenly over the potatoes. Return to the oven for 2–3 minutes, or until the cheese is melted and bubbly.
Carefully transfer the potatoes to a serving dish and sprinkle with chopped fresh chives. Serve immediately while hot and creamy.