Enchillada Casserole

E and I absolutely love Mexican food, so I continued to cook it without the cheese once C's allergies popped up. There are so many ways that I have played around with this type of casserole, but this one has been my favorite so far.

Enchillada Casserole
1 lb. ground beef
1/2 c. chopped onion
1 garlic clove, minced
1 t. chili powder
1 t. cumin
salt
1 jar chunky salsa
1 can black beans, rinsed and drained
1 c. frozen corn
soft tortilla shells

Spray a large skillet with dairy-free cooking spray and heat over medium-high heat. Cook onion and garlic for 1 minute, then add the ground beef and cook until browned. Drain any fat. Add the chili powder, cumin, salt, salsa, beans, and corn and simmer for 15 minutes. Spray a 9-inch cake pan with cooking spray. Layer the casserole with 2 tortilla shells, then the beef mixture and continue until you have 3 layers. Top with mexican blend cheese if you aren't restricted from dairy. Bake at 350 degrees for about a half hour. Serve with lettuce, tomato, and avocado.