Preheat oven to 450° F and then prepare a baking sheet with nonstick cooking spray or foil.
Cut potatoes into bit sized pieces and place in a large mixing bowl. Drizzle with oil and toss to coat. Add ranch seasoning and toss again to coat.
Place potatoes on a prepared sheet pan. Bake for 30-35 minutes or until potatoes are tender and brown. Remove from oven and top with shredded cheese. Broil in oven for 30-40 seconds or until cheese has melted. Serve with diced green onions.