Heat the oil in a large pan over medium heat. Add in chopped onions and caramelize. Once they start to soften add in ground beef. Chopped up the meat with the end of your spatual as you brown the meat.
Add in the taco seasoning and stir until it's mixed all through the meat.
Pour in beans and mix.
Spread about ¼ cup of enchilada sauce in baking dish bottom.
Layer 4 tortillas.
Add ½ of meat mixture and ½ of shredded cheese.
Pour ½ cup of enchilada sauce over cheese.
Repeat process.
Add once more set of 4 tortillas on top. Pour remaining sauce and sprinkle cheese.
Cover dish with foil and bake for 30 minutes. Uncover and bake for an additional 5-10 minutes or until cheese is melted and browned.
Top with tomatoes and green onions. Let cool for 5 minutes before cutting.
Recipe by A Camera & A Cookbook at https://acameraandacookbook.com/enchilada-stack/