InstructionsReset

1. Preheat oven to 400°. Drizzle cut sides of squash with 1 tablespoon oil; season with salt and black pepper. Arrange halves cut side down on a large baking sheet.
2. Roast squash until tender, 30 to 35 minutes. Let cool slightly. Using a fork, scrape squash strands into a large bowl. Reserve boat halves. Keep oven on.
3. Season chicken all over with salt and black pepper. In a large skillet over medium heat, heat 2 tablespoons oil. Add chicken and cook, turning occasionally, until golden brown and cooked through, about 8 minutes per side. Transfer to a cutting board and let rest 5 minutes, then cut into bite-sized pieces.
4. In same skillet over medium heat, heat remaining 1 tablespoon oil. Add garlic and cook, stirring, until fragrant, about 1 minute. Add milk and broth and bring to a simmer. Stir in cream, Parmesan, and red pepper; season with salt and black pepper. Return to a simmer and cook, stirring occasionally, until thickened, about 10 minutes.
5. To bowl with spaghetti squash, add chicken and sauce and toss to combine. Divide chicken mixture between reserved squash halves. Top with mozzarella.
6. Bake squash boats until warmed through and cheese is melty, about 15 minutes.
7. Arrange squash halves on a platter. Top with parsley.