In a large skillet over medium heat, add the ground beef and chopped onion. Cook until the beef is browned and the onion is soft, about 5-7 minutes. Drain any excess fat if necessary.
Add the garlic powder, taco seasoning, and water to the skillet. Stir to combine and let it simmer for about 5 minutes until the mixture thickens slightly.
Stir in the drained corn and salsa into the beef mixture. Cook for an additional 3-4 minutes until heated through. Remove from heat.
Preheat your oven to 350°F (175°C). Lay 3 tortillas on the bottom of a greased 9x13 inch baking dish. Overlap them slightly to cover the entire base.
Spread half of the beef mixture over the tortillas, followed by a layer of cheese. Repeat the layering with the remaining tortillas, beef mixture, and finish with a generous topping of cheese.
Cover the baking dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and golden.
Once out of the oven, let the Taco Pie rest for about 5 minutes. This helps with slicing and serving.
Top with your favorite garnishes such as diced tomatoes, sliced green onions, shredded lettuce, and a dollop of sour cream or guacamole. Serve warm and enjoy!