Prep the Jalapeño Popper Mixture: In a mixing bowl, combine the softened cream cheese, shredded cheddar cheese, diced jalapeños, garlic powder, onion powder, and black pepper. Stir until everything is thoroughly mixed and creamy. Set aside.
Form the Patties: Divide the 80/20 ground beef into four equal portions and shape them into patties. Make a slight indentation in the center of each patty so they cook flat and even.
Cook the Burgers: Heat a skillet or grill over medium-high heat. Cook the beef patties for about 4 to 5 minutes on the first side, then flip.
Add the Cheese Blend: Spoon a generous dollop of the cream cheese and jalapeño mixture onto each patty during the last couple of minutes of cooking. Cover the pan or grill briefly to let the cheese soften and melt into the burger.
Toast the Buns: While the burgers finish cooking, light toast the brioche buns until golden brown.
Assemble and Serve: Spread a little mayonnaise on the bottom bun if desired. Add the lettuce, top with the cheesy jalapeño burger, layer on the crispy bacon slices, and finish with the top brioche bun. Serve immediately while hot and gooey.