Mix softened cream cheese and blue cheese together, beating or mashing together with a fork, until blended. Set aside to give the flavors time to meld.
Season ground beef with salt and pepper or your choice of seasonings, form into 4 patties. Fry the slices of bacon until crisp, drain (I often fry my bacon on the grill with my hamburger patties). Grill the burgers until done. Spread mayo onto the toasted buns.
Just before removing the patties from the grill, top each patty with approximately 1/4 of the cream/blue cheese mixture, then place a slice of monterey jack cheese over the cheese mixture. As soon as the jack cheese starts to become gooey, remove the patties from the grill and place onto the buns. Top with bacon slices, lettuce, onions and tomatoes.
DO NOT USE KETCHUP! Ketchup and blue cheese DO NOT go together!