Preheat oven to 350°F.
Cook spaghetti until al dente. Drain well.
Heat oil in skillet. Add mushrooms and cook.
Remove mushrooms. Melt butter in skillet.
Add flour and whisk until smooth.
Slowly add broth, whisk until thick.
Add cream, garlic powder, salt, pepper.
Stir in chicken, mushrooms, peas, spaghetti.
Pour mixture into greased baking dish.
Top with mozzarella and Parmesan cheese.
Cover with foil, bake for 20 minutes.
Remove foil, bake until cheese is golden.
Garnish with fresh parsley before serving.
Serve hot and enjoy immediately.