- Preheat the oven to 425 degrees. Line a baking sheet with aluminum foil.
- Thinly slice the onions, separating green parts from the white and light green parts. Add white and light green parts to a large bowl. Reserve green parts for garnish.
- Add potatoes to the bowl with onions, toss with melted butter and spices. Spread the potatoes into an even layer on the baking sheet.
- Bake at 425 for 20 minutes, or until tender. Stir halfway through baking.
- Toss with green onion tops before serving.