Cook the bacon in a medium nonstick skillet over medium heat, stirring occasionally, until crispy, about 10 minutes. Drain on a paper towel-lined plate and set aside. For the dressing: Whisk the mayonnaise, parsley, sour cream, buttermilk, chives and garlic in a medium bowl until smooth. Season with the salt and black pepper. Combine the lettuce, tomatoes, scallions, bacon and all but 1⁄2 cup of the cheese in a large bowl. Add the dressing and toss to coat. Sprinkle with the remaining cheese.