Pre-heat oven to 425 and line a baking sheet with foil.
Place the first 10 ingredients in a large bowl (butternut squash through cayenne) and toss until evenly coated in oil and spices. Scatter into a single layer and roast until vegetables are caramelized and tender, about 30-35 minutes.
Pour mixture into a large soup pot and stir in the chicken broth and plain yogurt. Heat over medium high heat until warmed through. Check for seasoning and adjust accordingly before serving.
Optional: Lightly roast the reserved butternut squash seeds in olive oil, salt and pepper for 5-6 minutes while vegetables are roasting to garnish soup before serving.
roasted butternut squash seeds
Notes
Roasting the vegetables first is a great way to add depth of flavors to your soup. You could also try grilling the vegetables first!