Preheat the oven to 450°F. Line a sheet pan with parchment paper.
Peel and dice potatoes to ½-inch cubes and transfer them into a microwave-safe bowl. Microwave for 7 minutes at medium-high temperature, then leave them to cool for another 7 minutes.
Add the olive oil to the bowl of potatoes and toss to coat evenly. Put the potatoes on the sheet pan in a single layer and roast them for 15 minutes. Flip the potato cubes over and continue roasting for another 10 minutes.
While the potatoes are roasting, finely chop fresh scallions and place them into a small bowl.
Remove the potatoes from the oven and immediately sprinkle with parmesan cheese and rosemary, making sure the cheese is on top of the potatoes. Put the potatoes back into the oven to roast for 3 minutes, then remove and transfer them into a bowl.
Add paprika, garlic powder, onion powder, cayenne, black pepper, and salt into a separate bowl and stir to mix well. Add the mixture to the potatoes and toss to coat evenly.
Sprinkle with fresh scallions and serve hot.