1. Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.

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

3. Place squash halves cut-side down on the baking sheet and roast for 35 to 40 minutes until tender.

4. Meanwhile, season chicken breasts with salt and pepper and cook in a skillet over medium heat with olive oil for 6 to 7 minutes per side until internal temperature reaches 165°F (74°C), then shred.

5. Steam broccoli florets for 3 to 4 minutes until crisp-tender and drain well.

6. In a bowl, combine shredded chicken, broccoli, minced garlic, and pesto, then stir in half of the mozzarella and parmesan.

7. Flip roasted squash halves cut-side up and scrape strands with a fork, keeping them in the shell.

8. Divide the chicken mixture between the squash halves and toss gently to distribute.

9. Sprinkle remaining mozzarella and parmesan over the boats and bake for 10 to 12 minutes until cheese is melted and golden.

10. Garnish with red pepper flakes or chopped basil and serve.