Prepare the tortellini according to the package directions
Meanwhile, heat the oil in a large skillet over medium-high heat then add the chicken and cook for about 10 minutes, until cooked through and golden brown
Add the cooked, drained tortellini to the skillet
Stir the spaghetti sauce into the chicken and tortellini
Reduce the heat to low and sprinkle with the mozzarella cheese
Cover and cook for 3-5 minutes, until the cheese melts
Garnish with 1/4 cup of parmesan cheese if desired