Cook the pasta according to package instructions. When it is finished cooking, drain and set aside.
While the pasta is cooking, heat the oil in a skillet. When it is smoking, add the sirloin and cook until for about 5 minutes or until browned. Remove the meat from the skillet and tent loosely with foil. Drain any excess grease from the skillet, though there is no need to clean it.
Melt the butter in a large skillet. Add in the peppers, mushrooms, onion, and garlic, then add the salt and pepper. Cook until the vegetables are soft, about 5 minutes.
Whisk in the flour. Then slowly whisk in the half and half and the whole milk. Bring the milk to a simmer. Stir in the provalone and stir until compltely melted. Add the cooked noodles to the cheese sauce.
Finally stir in sirloin. Serve and enjoy!