Preheat oven to 200 degrees C. Place potatoes in a large roasting dish lined with baking paper. Spray with olive oil. Bake for 35-40 minutes or until tender and lightly golden.
Meanwhile, combine seeds, turmeric, cardamon, onion powder and salt in a small bowl. Add chickpeas and stir to combine. Heat oil in a medium ovenproof dish in oven with potatoes for 5 minutes.
Add chickpea mixture to hot oil and shake to coat. Return to oven and roast for 20-25 minutes, stirring once or until beginning to crisp.