Preheat the oven to 400°F (200°C). Cut the spaghetti squash in half lengthwise and scoop out the seeds. Place the halves cut-side down on a baking sheet.

Roast in the oven for 30-40 minutes, or until the flesh is tender and can be easily shredded with a fork.

In a skillet over medium heat, melt the butter. Add minced garlic and sauté for 1-2 minutes until fragrant.

Add the cooked chicken and spinach to the skillet. Cook until the spinach is wilted, about 3-4 minutes.

Pour in the heavy cream and bring to a simmer. Stir in the parmesan cheese, salt, and pepper. Cook for another 3-5 minutes until the sauce thickens.

Once the spaghetti squash is done, use a fork to shred the flesh into strands. Add the squash to the skillet with the chicken and spinach, then pour the alfredo sauce over the top.

Toss everything together until well combined. Serve hot, garnished with additional parmesan if desired.