Bring a large pot of salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.
Meanwhile, melt butter together with the olive oil in a saucepan over medium heat. Stir in onion, and cook until softened and translucent, about 2 minutes.
Stir in garlic, along with red pepper and mushroom (both optional); cook over medium-high heat until soft, about 2 minutes more.
Stir in the chicken, and cook until white on all sides, then pour in Alfredo sauce, Romano cheese, and cream; bring to a simmer stirring constantly until sauce is thickened and chicken is fully cooked, about 5-7 minutes.
Season with parsley flakes, cayenne, salt, and pepper to taste. Stir drained pasta into the sauce and serve immediately.