Steps
1. Cook spaghetti according to package instructions.
2. In a pan, sauté onions and garlic until fragrant.
3. Add mushrooms and cook until tender.
4. Stir in heavy cream, Parmesan cheese, salt, and pepper.
5. Toss cooked spaghetti in the creamy mushroom sauce.
6. Serve hot, garnished with fresh parsley.