Heat oil in a large pot over a medium heat. Add the onion and garlic, and stir until starting to soften.
Add the pumpkin, carrots and turmeric, stirring to coat in the spice mixture. Add the stock and 500ml water, and bring to the boil.
Reduce heat and simmer for 30 minutes, or until the vegetables are tender. Puree the soup using a stick blender until smooth. Divide among bowls, and top with a dollop of yoghurt and a sprinkle of pepitas and parsley.