01 - Preheat oven to 400°F. Cut zucchini in half lengthwise and scoop out the flesh with a spoon, leaving a ¼-inch thick shell. Reserve ½ cup of the scooped flesh and chop it finely.
02 - Arrange zucchini boats cut-side up on a baking sheet. Brush with 1 tablespoon olive oil and season with salt and pepper. Roast for 15 minutes until slightly softened.
03 - While zucchini roasts, heat remaining 1 tablespoon olive oil in a large skillet over medium heat. Add onion and cook for 2 minutes. Add garlic, reserved zucchini flesh, and butternut squash; cook for 8-10 minutes until squash is just tender.
04 - Stir in black beans, chili powder, cumin, smoked paprika, and ¾ cup enchilada sauce. Cook for 2-3 minutes until heated through and well combined. Remove from heat.
05 - Remove zucchini boats from the oven. Spoon the black bean and squash mixture evenly into each boat, packing lightly.
06 - Drizzle remaining ¾ cup enchilada sauce over the stuffed boats. Sprinkle shredded Monterey Jack or cheddar cheese evenly on top.
07 - Return to oven and bake for 15-20 minutes until cheese is melted and bubbly and zucchini is fork-tender.
08 - Top with crumbled queso fresco, fresh cilantro, avocado slices, and lime wedges. Serve immediately while hot.