In a large mixing bowl, combine beef, onion, bread crumbs, BBQ sauce, seasoned salt and pepper.
Gently press mixture in an even layer into a 9 x 13 inch baking pan sprayed with nonstick cooking spray.
Use the tines of a fork to poke holes throughout the meat.
Bake for 30 minutes (watching to make sure it doesn't burn).
When the hamburger is fully cooked, the meat will shrink away from the sides and liquid will accumulate around the edges of pan. At this point, remove the pan from oven and carefully drain off excess liquid.
Place slices of cheese in a single layer on top of the meat and return pan to oven for about 2-3 minutes or until the cheese starts to melt.
Remove from the oven and allow to rest for a few minutes.
Cut meat evenly into 6 patties and place in the middle of six lettuce leaves.
Top with ketchup, mustard, pickles and tomato if desired.
Top with another lettuce leaf, wrap up and enjoy.
*Nutrition info does not include optional toppings.
Notes
*Nutrition info does not include optional toppings.