Combine base: Whisk mayonnaise, sour cream, and buttermilk until smooth.
Add liquids: Whisk in lemon juice, vinegar, and Worcestershire sauce.
Season: Add garlic, parsley, dill, onion powder, pepper, salt, and cayenne. Whisk to combine.
Add most cheese: Reserve ¼ cup blue cheese. Fold remaining ¾ cup into dressing, mashing some while leaving chunks.
Add reserved cheese: Fold in reserved crumbles gently, keeping whole for texture.
Adjust: Add buttermilk to thin or more cheese to thicken. Taste and adjust seasoning.
Chill: Refrigerate minimum 30 minutes before serving. Stir before using.