Preheat your oven to 400°F (200°C). While it heats, wash and cut baby potatoes into halves or quarters (anything larger than a golf ball should be quartered). Slice the smoked sausage into 1/4-inch rounds—about the thickness of two stacked quarters.

In a small bowl, mix together the ranch seasoning, garlic powder, onion powder, and black pepper. Place the cut potatoes in a large bowl, drizzle with olive oil, and toss with the entire seasoning mixture until every piece is evenly coated.

Line a standard 18x13-inch baking sheet with parchment paper. Spread the seasoned potatoes in a single layer with space between each piece to allow for crisping. Scatter the sliced sausage pieces evenly over and around the potatoes.

Roast for 35-40 minutes, stirring gently at the 20-minute mark to ensure even browning. The potatoes should be golden brown with crispy edges and fork-tender. Remove from oven, immediately sprinkle the shredded cheese over everything, and return to oven for 5 minutes until cheese is melted and bubbly with golden spots forming at the edges.

Remove from oven and garnish with fresh chopped parsley if desired. Serve immediately with sour cream on the side.