In a large heavy-bottomed Dutch oven or stockpot (I used my 8-quart Dutch oven with plenty of room) warm 1-2 tablespoons of oil over medium heat. Add the chopped onions and sauté for 2-3 minutes or until soft and translucent. Add the minced garlic to the onion and mix. Cook for an additional 1-2 minutes, stirring continuously.
Add the diced bell pepper, cherry tomatoes, and butternut squash. Mix well with a wooden spoon or spatula to combine. Cook the vegetables for approximately 5 minutes, stirring often.
Add the diced tomatoes (with the liquid), chopped chipotle chilies, ancho, chili powder, ground cumin, salt, and pepper. Continue to cook, stirring constantly, for a minute or so.
Finally, add the zucchini, black beans, kidney beans, and water to the pot, mixing well to combine. Bring to a boil, cover, and reduce heat to low. Simmer for at least 20 minutes, or until the squash is fully cooked and fork tender.
Remove from heat and stir in the baby spinach or chopped kale, if desired. Season with additional salt and pepper, to taste.
Serve garnished with your favorite toppings such as avocado, shredded cheese, sour cream, or green onion. Enjoy!