Preheat oven to 350°F.
Use 1 tablespoon of the softened butter to grease the sides and bottom of a 1 1/2-quart baking dish.
Combine the cubed pasteurized cheese, cubed cream cheese, and shredded cheddar cheese in a bowl.
In a large bowl, gently toss the potatoes, chopped hardboiled eggs, crumbled bacon, green onion, and pimentos.
In a separate bowl, whisk the mayonnaise, sour cream, melted butter, apple cider vinegar, Worcestershire sauce, black pepper, and reserved bacon drippings.