In a large skillet over medium-high heat, crumble and brown ground beef until fully cooked, about 5-7 minutes. Drain excess fat, stir in enchilada sauce, water, and taco seasoning. Simmer for 5 minutes.

In a mixing bowl, combine ROTEL tomatoes with cream of mushroom soup. Stir until even, then fold in most of the shredded Mexican cheese blend, reserving 2 cups for layering.

Lightly spray the inside of your slow cooker. Begin layering by placing quartered tortillas at the bottom. Add half of the beef mixture, half of the cheese and soup mixture, sprinkle some reserved cheese, and repeat until all ingredients are used.

Cover the slow cooker and set to cook on high for 2 hours or low for 3-4 hours until bubbling and golden.

Let the casserole sit for a few minutes, then garnish with diced avocado and chopped cilantro before serving.