Preheat your oven to 350 degrees. Lightly mist a 9x13 dish with non-stick spray.
Stir together 3/4 cup of the Manwich sauce, eggs, bread crumbs, onion, salt, pepper, and meat. You might need to get messy and put your hands right in there to ensure that all of the ingredients are well combined.
Shape your mixture into a 9x5 rectangle in your prepared dish. Spread remaining sauce on the top and cook for 45 minutes or until an internal temperature of 160 degrees. Cool 10 minutes before slicing.