Preheat oven to 425. Spray 2 baking sheets and a 13 x 9-inch baking dish with nonstick spray.
Prepare Squash and Green Sauce:
Place squash on a baking sheet, then drizzle with olive oil and salt. Toss well.
Top the other baking sheet with the tomatillos, poblanos, garlic cloves, and onion. Drizzle with olive oil.
Place both baking sheets in oven on separate racks.
Roast vegetables for 15 minutes. Flip veggies, rotate trays, and continue roasting until all vegetables are browned and soft, about 10-15 more minutes.
Place poblanos in a zip top plastic bag (or a covered bowl) for about 10 minutes.
After 10 minutes, take poblanos out of bag, and carefully remove the seeds and as much skin as possible. Discard the stem.
Combine poblanos, tomatillos, garlic (remove skin), and onion, along with any juices, in a food processor. Process until smooth, then season to taste with salt, about ½ to 1 tsp. Set aside.
Assemble Enchiladas:
Drain a little liquid from the top of the black beans, then combine with chili powder, cumin, oregano, and salt. Mix well.
Stir bean mixture into roasted butternut squash (you can do this right on the baking sheet). Adjust seasoning if necessary.
Cover the bottom of the 9 x 13-inch baking pan with green sauce.
Warm tortillas one at a time in a small skillet on medium-high heat, flipping once. It should only take a few seconds; do not overcook the tortillas or they will get tough.
Top each tortilla as it comes out of the skillet with 1/12 of the butternut squash mixture, and 1/12 of the cream cheese.
Roll up tortillas and place in baking pan. Repeat process with remaining tortillas and filling ingredients.
Cover tortillas with remaining sauce, then sprinkle with Monterey Jack Cheese.
Bake enchiladas for about 20 minutes, or until hot and cheese is melted and lightly browned.
Serve enchiladas hot, topped with cilantro and avocado. Serve with a lime wedge. Enjoy!