1. Preheat the oven to 400°F and line a rimmed baking sheet with parchment paper or foil.

2. Cut the squash in half lengthwise, scoop out the seeds, brush the cut sides with olive oil, and season with salt and pepper.

3. Place the squash cut-side down on the baking sheet and roast until tender, about 35–40 minutes.

4. Let the squash cool slightly, then use a fork to scrape out strands, leaving the shells intact as boats.

5. In a skillet over medium heat, melt butter and sauté garlic until fragrant, about 30 seconds.

6. Stir in heavy cream and simmer lightly for 3–4 minutes, then whisk in cream cheese and Parmesan until smooth.

7. Season the sauce with salt, pepper, and nutmeg, then add shredded chicken and spinach, stirring until the spinach wilts.

8. Divide the Alfredo mixture among the squash boats and top each with shredded mozzarella.

9. Reduce oven temperature to 375°F, return the boats to the oven, and bake until cheese is golden and bubbly, about 10–15 minutes.

10. Remove from the oven, let rest for 5 minutes, garnish with fresh parsley, and serve.