How to Make It
Prepare the turkey: Stir together butter, thyme, garlic, rosemary, sage, lemon zest, 2 teaspoons of the salt, and 1 teaspoon of the pepper in a medium bowl until well incorporated. Rub butter mixture under turkey skin. Sprinkle outside of turkey with remaining 1 teaspoon kosher salt and 1/2 teaspoon black pepper. Pour chicken broth in bottom of a 6-quart slow cooker; add turkey, skin side up. Cover and cook on LOW until a thermometer inserted into thickest portion registers 165°F, 4 1/2 to 5 hours.
Remove turkey from slow cooker; remove skin from turkey and discard. Chop turkey and set aside, covered.
Prepare the dressing: Whisk together buttermilk, grated garlic, mayonnaise, sour cream, 2 teaspoons chopped fresh chives, flat-leaf parsley, 1 1/2 oz. blue cheese, salt, pepper, and paprika in a medium bowl.
Divide the iceberg lettuce quarters among 4 plates. Spoon dressing evenly over lettuce. Top each salad with 10 oz. chopped turkey (reserve the remaining turkey for another use), tomato, red onion, remaining blue cheese, and remaining chives.