Combine beef with bacon, chipotle paste, Worcestershire, garlic, onion, salt and pepper. Form 6 patties that are thinner at center and thicker at edges for even cooking. Drizzle with a little oil.
Heat a cast-iron skillet or double-burner griddle pan over medium-high heat.
Melt butter in a small pan over medium heat. Whisk in flour, cook 1 minute then add milk. Cook to thicken then melt in cheeses.
Meanwhile, grill the burgers 5 minutes on each side for medium, a minute less per side for rare, a minute more per side for medium-well.
Place burgers on bun bottoms and top with cheese sauce, chips and toppings. Set bun tops in place and serve.