1. Preheat the oven to 400 degrees.
2. Use a vegetable brush to wash the sunchokes clean.
3. Thinly slice them and place them on a greased cookie sheet.
4. Lightly spray the sunchokes with a little bit of cooking spray (or drizzle lightly with oil).
5. Sprinkle with salt, pepper, rosemary and garlic powder.
6. Roast for 25 to 30 minutes.