Preheat the oven to 200° C/390° F Fan.
Place a large pan over high heat and allow to get very hot. Add 2-3 tablespoons of olive oil and the mushrooms and sauté until golden.
Add the butter, salt, pepper, garlic, spinach, nutmeg and continue sautéing until the spinach has wilted.
Lower the heat to medium, add the cream cheese, heavy cream, broth and a little more salt and pepper. Allow the sauce to thicken slightly.
Add the parsley and remove the pan from the heat.
Pour the pasta into an ovenproof dish and pour the mushroom sauce over it.
Sprinkle over the grated mozzarella cheese and bake in the oven for 20-30 minutes.
Remove from oven, cut and serve.