Preheat the oven. Set it to 400°F (200°C).
Line a large baking sheet with parchment paper for easy cleanup.
Prep the zucchini. Slice each zucchini in half lengthwise. Use a spoon to scoop out the seedy center, leaving about 1/4 inch of flesh around the sides so the boats hold their shape.
Season the boats. Brush the cut sides with olive oil, then sprinkle with salt, pepper, garlic powder, and smoked paprika. Place them cut-side up on the baking sheet.
Par-bake the zucchini. Bake for 8–10 minutes to soften slightly.
This helps the boats cook through without becoming watery later.
Mix the filling. In a bowl, combine shredded chicken with 3/4 cup sugar-free BBQ sauce. Taste and add more sauce if you prefer a saucier filling. Season with a pinch of salt and pepper if needed.
Fill and top with cheese. Spoon the BBQ chicken into the warm zucchini boats, packing it in evenly.
Mix mozzarella and cheddar together, then sprinkle generously over the top.
Bake again. Return to the oven for 10–12 minutes, until the cheese is melted and lightly golden.
Finish and garnish. Let the boats rest for 3–5 minutes to set. Drizzle a little extra BBQ sauce if you like, then top with sliced green onions and chopped cilantro or parsley.
Serve hot. Pair with a simple side salad, cauliflower “potato” salad, or grilled veggies.