Bring a pot of water to a boil for the pasta and heat a cast-iron skillet or large griddle pan over medium-high heat.
Combine meat with Worcestershire, grated onion, salt and pepper, and form patties, 4 large or 8 small. Drizzle patties lightly with oil. Separate buns and arrange bottoms on a platter.
Undercook the macaroni by a minute in boiling salted water. Meanwhile, melt butter in a small pan over medium heat. Add garlic and chilies, and stir 3 minutes. Add pimientos and heat through. Add paprika then flour and stir 1 minute. Whisk in milk and let thicken. Season with salt and pepper then stir in cheese to melt. Add macaroni and stir to combine.