Preheat oven to 350° F. Heat a large skillet over medium-high heat and spray it with cooking oil. Add in the ground beef and crumble it. Add in the chili powder, cumin, oregano, and garlic powder and season with salt, pepper. When the beef is mostly cooked through add in the diced onion. Sauté for several minutes until it’s softened. 

Add in a 1/4 cup of water to the ground beef mixture. Let is simmer for 2-3 minutes and then stir in the green chiles, black beans, corn, and 2/3 cup of salsa. Let everything heat through for about 2 minutes and then remove the skillet from the heat.

Spread the remaining 1/3 cup of salsa on the bottom of a 9x13 baking dish. Place 3 of the corn tortillas into the baking dish. Cut one of the tortillas in half so that the bottom is completely covered by the tortillas. Spoon half of the ground beef mixture on top of the tortillas and spread it out until they’re covered. Top with half of the cheese. Repeat the process once more.

Cover the baking dish with foil and put it in the oven. Bake for 25 minutes and then remove the foil and bake for another 10 minutes or until it’s hot and bubbly. Remove the casserole from the oven and top it with your favorite taco toppings.