Follow these simple steps to create a delicious Turkey Tetrazzini with Spinach:

1. Preheat your oven to 375°F (190°C).
2. Cook the spaghetti according to package instructions until al dente. Drain and set aside.
3. In a large skillet, heat olive oil over medium heat. Sauté the onion and garlic until translucent.
4. Add the sliced mushrooms and cook until tender, about 5 minutes.
5. Stir in the chopped spinach and cook until wilted, about 2-3 minutes.
6. In a mixing bowl, combine the turkey, cooked spaghetti, sautéed vegetables, chicken broth, heavy cream, thyme, salt, and black pepper. Mix well.
7. Transfer the mixture into a greased 9×13 inch baking dish. Spread evenly.
8. Sprinkle grated Parmesan cheese over the top, followed by breadcrumbs if using.
9. Cover with aluminum foil and bake in the preheated oven for 20 minutes.
10. Remove the foil and bake for an additional 10 minutes, or until the top is golden and bubbly.
11. Let cool for a few minutes before serving.

With these steps, you’re well on your way to enjoying an amazing dish that everyone will love.