Roast the butternut squash- Preheat oven to 375 degrees F and line two large baking sheets with parchment paper.
Using a large, sturdy knife to cut ends from the butternut squash and slice the skin using a vegetable peeler or paring knife. Cut the squash in half lengthwise. Scoop out the seeds and stringy bits from each half and discard seeds (or save for roasting).
Cut the squash into cubes and toss with olive oil, salt, and pepper. Transfer to the prepared baking sheets and bake for approximately 25 minutes, or until cooked to desired doneness.
As the butternut squash is cooking, heat the remaining olive oil in a large pot or Dutch oven over medium-high heat. Add the onion and shallots and mix well to combine. Sauté for 3-4 minutes, stirring frequently. Add the chopped carrots and celery and stir to combine. Cook, stirring frequently, for an additional 5 minutes.
Stir in the garlic, salt, pepper, taco seasoning, and cayenne. Mix well and cook for one minute before adding the vegetable broth and water. Increase heat to high and bring to a boil. Reduce heat to low, cover, and simmer for approximately 10 minutes.
Drain and rinse two (15-ounce) cans of black beans. Add the drain black beans and half of the butternut squash to the pot. Cover and cook for an additional 5 minutes.
Working in batches, puree the soup, only filling the bowl of your blender half way to prevent accidents. Once the entire pot of soup has been completely pureed into a smooth and creamy soup, season to taste (it will probably need more salt). If soup is too thick, add additional water or broth until desired consistency is reached.
Garnish soup with sour cream, fresh cilantro, green onion, pumpkin seeds, additionally roasted butternut squash, and crushed tortilla chips, if desired.