Cook the Pasta: Bring a large pot of salted water to a boil. Cook the pasta according to the package instructions until al dente. Drain and set aside.
Sauté the Vegetables: In a large skillet, melt the butter over medium heat. Add the frozen vegetables and cook for 2–3 minutes until heated through.
Make the Sauce: Sprinkle the flour over the vegetables and stir to coat. Gradually whisk in the milk and chicken broth, stirring constantly to avoid lumps. Add garlic powder, onion powder, salt, and pepper. Cook for 5–7 minutes, or until the sauce thickens.
Add Chicken and Pasta: Stir in the shredded chicken and cooked pasta, ensuring everything is evenly coated in the sauce.
Optional Cheese Topping: If desired, sprinkle shredded cheddar cheese over the top and cover the skillet for 2–3 minutes to melt the cheese.
Serve: Garnish with chopped parsley and serve hot.