Preheat your oven to 400°F (200°C). Peel, seed, and cube the butternut squash into evenly sized pieces.
Toss the squash cubes with olive oil, salt, and pepper. Spread them on a baking sheet and roast for about 25-30 minutes until tender and slightly caramelized.
While the squash is roasting, finely dice the yellow onion and mince the garlic. In a medium pot, sauté the onion and garlic over medium heat until softened and fragrant.
Add the roasted squash to the pot along with the vegetable broth. Bring to a simmer and let it cook together for about 5 minutes to meld the flavors.
Using an immersion blender or regular blender, carefully blend the mixture until smooth. Return the soup to the pot if needed.
Stir in the nonfat Greek yogurt until well incorporated, giving the soup a rich, creamy texture. Adjust seasoning with salt, pepper, and a pinch of ground nutmeg.
Gently fold in the chickpeas. Warm the soup through on low heat for an additional 3-5 minutes without boiling, to preserve the creaminess.
Serve hot and enjoy your nutritious and satisfying roasted butternut squash soup.