Preheat your oven to 375°F (190°C). Spray a baking dish with cooking spray and set aside. Cook the pasta according to the package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the diced onion and cook until softened, about 3-4 minutes. Add the sliced mushrooms and cook until they release their moisture and start to brown, about 5 minutes. Add the thawed green peas and cook for an additional 2 minutes. Remove the onion, mushrooms, and peas from the skillet and set aside.
In the same skillet, melt the reduced-fat butter or olive oil spread over medium heat. Add the minced garlic and cook for about 1 minute until fragrant.
Sprinkle the flour over the garlic and butter mixture and cook, stirring constantly, for about 2 minutes to make a roux.
Gradually whisk in the chicken broth and skim milk until smooth. Cook, stirring constantly, until the mixture thickens, about 5-7 minutes.
Add the reduced-fat cream cheese to the sauce, stirring until melted and well combined. Season with salt and pepper to taste.
Add the cooked pasta, shredded cooked chicken, cooked onion, mushrooms, peas, and 1/2 of the Parmesan cheese to the skillet, tossing until everything is evenly coated with the sauce.
Transfer the mixture to the prepared baking dish. Sprinkle the remaining shredded Parmesan cheese on top of the pasta. Top with parsley.
Bake in the preheated oven for 20-25 minutes, or until the top is golden brown and the sauce is bubbly. Let it cool for a few minutes before serving.
This makes 6 servings. Each serving is 1.5 cups and is 11 WW Points. Enjoy!