Cheesy beef crumbles and all of your favorite toppings are piled high in the best cheeseburger sub you've ever had!
Place the ground beef in a large nonstick skillet set over med/high height. Break up the beef and let it begin to brown.
Add the onion and stir well. Let the beef brown, then drain off the fat. (I use a colander).
While the beef cooks, whisk together all the ingredients for the sub sauce.
Season the beef well, add the worcestershire sauce, and then add in the cheese. Stir until it begins to melt. Turn off the heat.
Split each roll lengthwise on top, but don't cut fully through the bottom. Scoop out some of the bread from the middle and spread each sub roll with some mayonnaise.
Divide the beef between the rolls. Drizzle with sub sauce and sprinkle with parmesan. Top with lettuce, tomatoes and onion and serve.