Cook the Pasta: In a large pot, bring salted water to a boil and cook the spaghetti or fettuccine according to package instructions until al dente. Drain and set aside.
Sauté Vegetables: In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sliced mushrooms, cooking until they are soft, about 5-7 minutes.
Make the Sauce: Stir in the chicken broth, heavy cream, garlic powder, and onion powder. Let it simmer for a couple of minutes to meld the flavors.
Combine Ingredients: In the skillet, add the shredded chicken, cooked pasta, and frozen peas. Mix everything together so that the sauce fully coats the pasta and proteins.
Pour into Baking Dish: Transfer the mixture into a greased 9x13 inch baking dish.
Add Toppings: Sprinkle the grated Parmesan cheese and breadcrumbs evenly over the top.
Bake: Preheat your oven to 350°F (175°C) and bake for 25-30 minutes or until the top is golden and bubbly.
Serve: Let it cool for a few minutes, then serve warm and enjoy!