01 - Preheat oven to 400°F.
02 - Cut zucchini in half lengthwise. Scoop out flesh with a spoon, leaving a ¼-inch thick shell. Reserve ½ cup of the scooped flesh and chop 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.
04 - Heat remaining olive oil in a large skillet over medium heat. Sauté onion for 2 minutes, then add garlic, chopped zucchini flesh, and butternut squash. Cook 8-10 minutes until squash is tender.
05 - Stir in black beans, chili powder, cumin, smoked paprika, and ¾ cup enchilada sauce. Simmer 2-3 minutes, then remove from heat.
06 - Remove zucchini boats from oven. Distribute black bean and squash mixture evenly among each boat.
07 - Drizzle remaining enchilada sauce over stuffed boats and sprinkle with shredded cheese.
08 - Return to oven and bake 15-20 minutes until cheese is melted and bubbly and zucchini is fork-tender.
09 - Top with queso fresco, cilantro, avocado slices, and lime wedges as desired. Serve immediately.