In a large mixing bowl, combine the shredded birria beef, cooked rice, black beans, corn, diced onion, minced garlic, cumin, chili powder, salt, and pepper.
Stir in the birria sauce until everything is well coated.
Transfer the mixture to a greased baking dish.
Sprinkle the shredded cheese evenly over the top.
Bake in the preheated oven for 30-35 minutes, or until the cheese is melted and bubbly.
Let the casserole cool for a few minutes before serving.
Notes:
Feel free to add your favorite toppings like sour cream, avocado, or fresh cilantro.