Cut squash in half and scoop out seeds. Place cut sided down in a greased baking pan and roast for about 45 minutes (until soft) at 350 degrees F. Remove from oven and let cool 15 minutes. Remove soft flesh and mash in bowl. Set aside.
In a large stockpot, heat oil over medium heat. Sauté onion for 5 minutes. Add garlic and sauté another minute.
Chop up roasted peppers and add to pot. Sauté another minute.
Add squash, tomatoes, beans, chili powder and cumin. Stir well and cover; cook on medium-low heat for about 30 minutes.
Serve with dollop of plan Greek yogurt, shredded cheese and fresh cilantro.
Let chili sit in refrigerator overnight for the flavors to meld together. It tastes even better as leftovers!