In a large skillet over medium high heat, cook ground beef and onion until ground beef is no longer pink and onion is softened. Drain any excess grease.
Stir in 1/4 cup of water and 1 packet or 3 TBS taco seasoning. (search for my recipe Homemade Taco Seasoning, for your own blend)
Stir in rotel tomatoes, diced tomatoes and enchilada sauce. Cook for 2-3 minutes. Turn off heat.
Spray inside of crockpot with a non-stick cooking spray. Place 1 layer of quartered tortillas into bottom of crockpot, overlapping if necessary. Spoon in 1/3 of the meat mixture over the tortillas evenly.
Sprinkle 4 oz of shredded cheese over meat mixture. Place another layer of quartered tortillas to cover the cheese. Pour 1/2 can of corn over tortillas. Pour 1/2 can of olives over tortillas. Place 4 oz of cheese over corn and olives.
Place another layer of tortillas over cheese. Add 1/3 of meat mixture over tortillas. Top with a layer of tortillas. Put rest of meat mixture, corn and olives on top of tortillas. Place 4 oz of cheese on top.
Cover crockpot with lid and cook for 2-3 hours on high or 4-6 hours on low. Turn off crockpot and all casserole to sit for 30 minutes before scooping. Garnish with green onion slices, sour cream and/or cilantro.