Wash the squash, cut off the ends, halve it, and remove the seeds and strings from the center. If you're using butternut squash, peel it first. Then, cut the squash halves into cubes.
Peel and mince the garlic cloves.
Heat the oil in a large pot and sauté the minced garlic over medium heat until fragrant and just beginning to brown.
Add the cubed squash and spices (turmeric, cumin, sumac) to the pot, and sauté briefly until the spices become fragrant.
Stir in the vegetable broth, tomato passata, and chickpeas.
Bring everything to a boil, then reduce the heat, cover, and simmer for about 20 minutes, or until the squash is tender (the time may vary based on the size of the squash cubes).
Once the squash is soft, turn off the heat and purée the soup using an immersion blender or in batches with a regular blender.
Add salt to your taste.
Serve the soup garnished with extra chickpeas and parsley leaves.