Preheat oven to 350°F (175°C).
Cook the penne pasta according to package instructions until al dente. Drain and set aside.
In a large skillet, heat olive oil over medium-high heat.
Add the chicken pieces and cook until browned and cooked through, about 6-8 minutes. Remove chicken from skillet and set aside.
In the same skillet, add diced onion and cook for 3 minutes until softened.
Add minced garlic, broccoli florets, sliced carrots, and sliced mushrooms. Cook for 5 minutes until vegetables are tender-crisp.
Reduce heat to medium-low and add butter to the skillet. Once melted, pour in the heavy cream and stir to combine.
Add grated Parmesan cheese, Italian seasoning, salt, black pepper, and crushed red pepper flakes. Stir continuously until the sauce thickens, about 3-4 minutes.
Return the cooked chicken to the skillet and stir to coat with the Alfredo sauce.
Add the cooked penne pasta to the skillet and gently toss everything together until well combined.
Remove from heat and stir in chopped fresh parsley.
Transfer the mixture to a 9×13-inch freezer-safe baking dish and let cool completely.
Cover tightly with aluminum foil or a freezer-safe lid and freeze for up to 3 months.
To reheat, thaw the freezer meal overnight in the refrigerator.
Preheat oven to 350°F (175°C) and bake, covered, for 25-30 minutes until heated through and bubbly.