In a large skillet on medium-high heat, heat the oil and add the onions. Saute the onions for 4-5 minutes. Remove onions from the skillet and set aside. To the same skillet, add the beef and cook until browned, 5-6 minutes. To the meat, add back in the cooked onions, the Rotel, enchilada sauce, and taco seasoning. Stir and simmer until liquid has evaporated. Add the cream cheese and sour cream. Turn off the heat and stir until combined. Add in the black beans; gently stir.
Take a 9x13 baking dish and prepare with non-stick cooking spray. Add ½ of the corn chips to the bottom of the pan. Top with ½ of the meat mixture, and 1 cup of cheese. Repeat the layers with chips, the rest of the meat mixture, and the remaining cheese.
TIP: If you use the large corn chips, you can crunch them first in the package with your hands to break them apart in smaller pieces. This step is optional, if you don’t like large chunks of the chips in the casserole.
Bake at 350 degrees for 15 minutes; until the casserole is cooked through and the cheese is melted on top.
Top with chopped green onions and serve!
Optional to serve with more sour cream, salsa, or guacamole, or other "taco" toppings (see list above).
Notes
Calories will be less without all of the additional toppings!