Before you start making the dressing, make sure you have all the ingredients on hand. You'll need Greek yogurt, Hidden Valley Ranch seasoning mix, garlic powder, onion powder, salt, black pepper, and milk (optional). You can find the ranch seasoning mix in the spice aisle of most grocery stores.
In a medium bowl, whisk together the Greek yogurt, ranch seasoning mix, garlic powder, onion powder, salt, and black pepper until smooth. If the dressing is too thick for your liking, you can add in some milk to thin it out. Start with a tablespoon at a time until you reach your desired consistency.
Once you've mixed everything together, give the dressing a taste and see if it needs any adjustments. You can add more seasoning, salt, or pepper if it's too bland, or more yogurt or milk if it's too strong. Keep in mind that the flavors will intensify as the dressing sits in the fridge, so you may want to err on the side of caution and start with less seasoning.
Once you're happy with the taste and consistency, transfer the dressing to a container with a tight-fitting lid and refrigerate for at least an hour before serving. This will give the flavors a chance to meld together and the dressing to thicken up. You can serve the dressing with a variety of salads, veggies, or chips, or use it as a dip for your favorite appetizers.