Preheat and prep the squash: Heat the oven to 400°F (200°C). Carefully halve the spaghetti squash lengthwise and scoop out the seeds. Rub the cut sides with a little oil and season with salt and pepper. Place cut-side down on a parchment-lined sheet and roast 35–45 minutes, until the strands pull away easily with a fork.

Cool and shred: Let the squash cool until you can handle it. Use a fork to scrape out the strands. Pat them dry with paper towels or squeeze gently in a clean towel to remove excess moisture. This step keeps your bake from getting watery.

Sauté the aromatics: In a large skillet over medium heat, warm 1 tablespoon oil. Add the diced onion and cook until soft and translucent, 4–5 minutes. Stir in the garlic and cook 30 seconds, until fragrant.

Build the sauce: Lower the heat. Add the cream cheese and stir until mostly melted. Pour in the heavy cream and chicken broth, whisking until smooth. Add Italian seasoning, red pepper flakes if using, and a pinch of salt and pepper. Simmer gently for 2–3 minutes to thicken slightly.

Melt in the cheese: Stir in 1 cup mozzarella and 1/2 cup Parmesan until the sauce turns silky and thick. Taste and adjust seasoning. You want it a touch saltier than usual since it’ll coat the squash and chicken.

Combine: In a large bowl, add the shredded spaghetti squash and chicken. Pour the cheese sauce over the top and toss until everything is well coated.

Assemble the bake: Grease a 9x13-inch baking dish. Spread the mixture evenly. Top with the remaining 1/2 cup mozzarella and a light shower of extra Parmesan.

Bake: Reduce oven temp to 375°F (190°C). Bake 18–22 minutes, until bubbly around the edges and the top is golden in spots. If you want more color, broil for 1–2 minutes.

Rest and garnish: Let it sit 5–10 minutes to set. Sprinkle with chopped parsley or chives. Slice, scoop, and serve hot.