Cook about 8 slices of bacon in a skillet over medium heat until crispy, roughly 8–10 minutes.

Transfer the bacon to a paper towel-lined plate to drain excess grease, then crumble into small pieces.

In a large mixing bowl, gently combine 1 pound of ground beef with the crumbled bacon, ¾ cup of panko breadcrumbs, and ¼ cup of milk.

In a separate bowl, whisk together 1 beaten egg, ½ diced yellow onion, 2 minced garlic cloves, 1 tbsp of Worcestershire sauce, and 1 tbsp of Dijon mustard.

Pour the wet ingredients into the meat mixture. Season with salt and pepper, then combine gently.

Take a small amount of the meat mixture and flatten it in your palm; place a cube of sharp cheddar cheese in the center.

Bake at 400°F (200°C) for 20–25 minutes or pan-fry for 8–10 minutes, then cover for an additional 5–7 minutes.

While cooking, prepare the burger sauce by mixing ½ cup of mayonnaise, ¼ cup of ketchup, 1 tbsp of yellow mustard, and other ingredients.

Serve the meatballs in toasted buns topped with lettuce, tomato slices, red onion, and pickles.