Preheat your oven to 375 degrees Fahrenheit.
Put the diced butternut squash on a baking sheet, drizzle with olive oil and season with salt and pepper. Roast in the oven until tender, about 20-25 minutes.
Meanwhile, sauté the onion and garlic in olive oil over medium heat until onion is softened, about 5 minutes.
Add the rinsed and drained black beans to the onion and garlic and cook for another couple of minutes until heated through.
Once the butternut squash is done roasting, add it to the pan with the onions and beans and stir well.
Pour a little enchilada sauce in the bottom of a baking dish, just enough to cover the bottom.
Fill each tortilla with the butternut squash and black bean mixture, roll up, and place seam side down in the baking dish.
Pour the rest of the enchilada sauce over the rolled tortillas, top with shredded cheese.
Put back into the oven until the enchiladas are heated through and the cheese is melted and browning, about 15-20 minutes
Serve topped with chopped cilantro for garnish, if desired.