• Preheat the oven to 350°F (175°C). Lightly grease a 2-quart casserole dish.
• Cook the pasta according to package instructions. Drain well and return to the pot. Toss the spinach with the hot pasta, cover the pot, and set aside.

Cook the chicken:

• In a large skillet or Dutch oven, heat 2 tablespoons of olive oil over medium-high heat. Add the chicken and cook until no pink remains, about 5–7 minutes. Transfer the cooked chicken to the pot with the pasta and spinach. Cover to keep warm.

Make the sauce:

• In a medium saucepan, heat the remaining 2 tablespoons of olive oil over medium heat. Add the garlic and cook for 1 minute, stirring frequently. Sprinkle in the xanthan gum (or flour) and whisk well

Add liquids:

• Pour in the white wine and heavy cream, stirring constantly. Continue cooking until the sauce thickens, about 5–6 minutes. *See Notes

Season the sauce:

• Stir in the Italian seasoning, nutmeg, salt, and pepper. Remove the saucepan from the heat and stir in the Parmesan cheese and sun-dried tomatoes.

Combine everything:

• Add the pasta mixture to the Dutch oven or skillet and stir to combine. Transfer the mixture to the prepared casserole dish.

Toast the bread crumbs:

• In a small skillet, melt the butter over medium-high heat. Add the bread crumbs and cook, stirring frequently, until browned and toasted, about 3 minutes. Stir in the chopped parsley.

Assemble and bake:

• Sprinkle the toasted bread crumbs evenly over the pasta. Bake in the preheated oven until the top is golden brown and bubbly, about 20–25 minutes.