Cook pasta as directed. Add broccoli to pasta 3 minutes before pasta is ready. Drain. In pan, over medium heat, add oil, onion and chicken. Season with salt and pepper. Saute until cooked through, 5-7 minutes. In a small sauce pan, heat butter, flour, cayenne, paprika, and garlic powder continually stirring. Wisk in milk and stock and bring sauce to boil. Simmer until it thickens. Add cheese and mustard to sauce and stir until melted. Mix, chicken ,pasta, broccoli, and sauce together and serve.