01 - Set oven to 400°F for roasting the zucchini boats.
02 - Cut zucchini in half lengthwise and scoop out flesh with a spoon, leaving a ¼-inch thick shell. Reserve ½ cup of the scooped flesh and chop it finely.
03 - Place 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.
04 - Heat remaining 1 tablespoon olive oil in a large skillet over medium heat. Add onion and cook 2 minutes. Add garlic, reserved zucchini flesh, and butternut squash; cook 8-10 minutes until squash is fork-tender.
05 - Stir in black beans, chili powder, cumin, smoked paprika, and ¾ cup enchilada sauce. Simmer 2-3 minutes until flavors meld. Remove from heat.
06 - Remove zucchini from oven. Spoon the black bean and squash mixture evenly into each boat, pressing gently to pack filling.
07 - Drizzle remaining ¾ cup enchilada sauce over stuffed boats and sprinkle evenly with shredded cheese.
08 - Return to oven and bake 15-20 minutes until cheese is melted and bubbly, and zucchini is completely tender when pierced with a fork.
09 - Top with queso fresco, fresh cilantro, avocado slices, and lime wedges. Serve immediately while hot.