For the potato salad, preheat oven to 450ͦF. Coat the potatoes and shallots with cooking spray and season with salt, pepper, garlic and onion. Roast potatoes cut-side down for 25 minutes; turn over and cook 10 more minutes to very crisp.
Whisk dressing in a large mixing bowl, add warm potatoes and toss. Cool to almost room temp then fold in cress.
Lower oven temp to 375ͦF after the potatoes come out. Bake bacon on a slotted pan or wire rack set on a rimmed baking sheet. Bake bacon 18 minutes to very crisp.
Place cream cheese in a food processor, add shredded cheese, port, garlic and horseradish, and pulse to combine into pub cheese; transfer to a bowl.
Combine beef with Worcestershire and salt and pepper then form 4 patties thinner at center and thicker at edges for even cooking. Preheat a cast-iron skillet over medium-high heat. Drizzle burgers with oil and cook patties 8 minutes, turning occasionally.
Assemble burgers: toasted bottom of roll, pickles, lettuce, tomato, onion, bacon, burger patty, pub cheese spread, another burger patty and the bun top.
Serve burgers with potato salad alongside.