Heat griddle over medium heat to about 400℉. *If cooking burgers on the stovetop, heat large skillet over medium heat.
Add half of the diced bacon to the griddle or skillet, and cook until crispy. Then transfer to paper towels to drain excess grease.
While the bacon is cooking, sauté the diced jalapeños in a separate area on the griddle just until barely tender. Then transfer to a medium bowl.
Make the popper-style burger topping. Add softened cream cheese and shredded cheddar cheese to the bowl with the sautéed diced jalapeños. Mix well and set aside.
Butter the cut side of the hamburger buns, and toast cut side down on the griddle until golden brown. Then remove from the griddle and set aside.
Divide ground beef into 6 equal portions, and roll each into a ball. *TIP - You can also use a 1/3 cup measuring cup to portion out equal amounts of beef.
Place 6 portions of diced raw bacon on the griddle in a round, even layer similar to the size of your burger balls. Set the beef balls on top of the bacon, and pile the sliced onions and sliced jalapeños on top of the balls. Allow the burger balls to cook untouched for about 1 minute like this for the bacon to begin the cooking process.
Use a burger press or stiff spatula to apply even pressure to the burger balls, smashing them down into a thin layer on the griddle or in the skillet. After smashing, continue to apply pressure for about 10 seconds.
Season the top side of the smash burger patties with burger seasoning or salt and pepper. Then allow the burgers to cook on the first side untouched for about 2-3 minutes.
When burgers are a bit more than halfway cooked through (and there are still some pink spots on top), use a spatula or scraper to flip the burgers to the second side, making sure to scrape under the bacon and burger crust to remove it from the griddle with your burgers. Immediately after flipping, top each patty with some of the jalapeno cream cheese mixture.
Cook on the second side for about 2-3 minutes, or until burgers are cooked through and the cheese mixture is warmed. *TIP - I recommend placing a melting dome over the burgers after adding the jalapeno cream cheese. If cooking burgers in a skillet, you can place a lid on the skillet to help melt the cheese more quickly without overcooking the burgers.
When burgers are done cooking, stack two burger patties on top of each other to make double smash burgers. Use your spatula to remove jalapeno popper smash burgers from the griddle, and transfer to the toasted buns. Serve warm.