Preheat oven to 350 degrees. Lightly rub or spray a baking sheet with olive oil. Spread chickpeas out in a single layer on the sheet.

Roast about 20 minutes, or until chickpeas are dry to the touch. Remove from oven, and increase temperature to 425 degrees (double-roasting the chickpeas gives them a crunchy texture). Place chickpeas in a large bowl. Pour in olive oil, and stir to coat. Add garlic powder, onion powder, rosemary, and salt. Stir again.

Place chickpeas back on the baking sheet. Roast another 15-20 minutes, or until crispy and lightly browned. Let cool completely before serving or storing at room temperature.