salt and freshly ground black pepper to taste (optional)
Fill a large pot with lightly salted water and bring to a rolling boil. Stir in tortellini and return to a boil. Cook uncovered, stirring occasionally, until the tortellini float to the top and the filling is hot, about 3 minutes.
Run tortellini under cold water and drain. Store in the refrigerator until chilled, at least 30 minutes.
Stir ranch dressing and milk together in a large bowl. Add chilled pasta, cooked chicken, mozzarella, bacon, green onions, and parsley.
Toss to combine. Season with salt and pepper if desired.