Brown hamburger, onion and green pepper together until hamburger is no longer pink. Drain off extra fat.
Turn off heat and stir in the rest of the ingredients. I like to pop the hash browns into the microwave for about 5 minutes (stirring midway through) before I stir them into the mixture (to reduce the final baketime), but this is not necessary.
Spray lube a 9x11 baking dish and pour in mixture. Sprinkle the Ritz crackers or Panko bread crumbs over top if desired. Cover tightly with aluminum foil.
Bake 35-45 minutes or until hot and bubbly. If you use the crackers or bread crumbs, remove foil for last 5 minutes to brown the top.