Combine the Parmesan cheese, yogurt, salt, mayonnaise, pepper, green onion, and parsley in a medium bowl.
If you want the dressing thinner you'll want to add the milk, a little at a time. While whisking, slowly add some of the milk. Whisk and see if the consistency is how you want it. If you want it thinner continue adding and whisking until you've got it how you want it.
Taste and add more salt and Parmesan as desired.
Refrigerate for 1 hour or overnight before serving.
Notes
For the best results, use freshly-grated Parmesan.Need ideas for putting together the ultimate salad? Check out my salad inspirations!