Roasted Pumpkin Soup with Crispy Chickpeas

• 700 g kent pumpkin, cut in large chunks
• 2 carrots, cut in large chunks
• 2 brown onions, cut in wedges
• 2 parsnips, cut into large chunks
• 1 bulb garlic, top sliced off
• 2 sprigs thyme
• 4 cup vegetable stock
• 2 tbsp extra virgin olive oil
• 0.5 cup Greek yoghurt
• 400 g tin chickpeas
• 2 tsp paprika
• 2 tsp cumin