Cook the cheese tortellini pasta according to the package instructions until al dente. Drain and set aside.
In a large skillet, heat the butter over medium-high heat. Add the sliced onions and mushrooms (if using) and sauté until soft. Add the thinly sliced beef and Worcestershire sauce to the skillet and cook until browned and cooked through.
Add the beef broth and the cooked cheese tortellini to the skillet with the beef and vegetable mixture. Toss gently to combine.
Sprinkle the cheese over the top of the pasta mixture. Cover the skillet with a lid and let it sit for a few minutes until the cheese is melted and bubbly.
Garnish with freshly chopped parsley and enjoy!