Preheat the oven to 375 degrees . Arrange the bacon on a broiler pan or rack set over a foil-lined baking sheet. Bake until crisp, 15 to 17 minutes.
Preheat a cast-iron or other heavy skillet over medium-high heat. In a small bowl, stir together the blue cheese and butter.
In a large bowl, combine the ground meat, worcestershire, parsley, some salt and lots of pepper. Form into 4 patties (thinner at the center and thicker at the edges, for even cooking).
Drizzle the hot pan with EVOO. Add the patties and cook, turning once, for 8 minutes for medium-rare beef or 12 minutes for turkey.
Season the tomato with salt and pepper. Dress the avocado with the lemon juice.
Place the burgers on the bun bottoms and slather with the blue cheese butter. Layer with the bacon, lettuce, tomato, avocado, onion and bun tops.
