Preheat oven to 170°C fan bake.
Heat a large pan over medium heat. Add the beef mince and diced onion. Cook until the mince is browned and the onion has softened.
Add the nacho powder, garlic powder, onion powder, and salt. Stir through to evenly coat the mince.
Add the tin of beans, tomato paste, water, and frozen corn. Mix well and bring to a gentle simmer.
Let the filling cook for 5–7 minutes, or until slightly thickened.
On an oven tray or in two baking dishes, place the first tortilla down.
Add a spoonful of the hot mince mixture, sprinkle over a generous handful of cheese, then repeat with 5–6 layers for each stack.
Finish each stack with a final tortilla and plenty of cheese on top.
Bake for 10–15 minutes, or until the cheese is golden and everything is heated through. Cover with foil if the top is browning too quickly.
Top with mashed avocado, whipped sour cream, and sprinkle with spring onions or fresh parsley. Slice and serve warm.