Preheat the oven to 180ºC (350ºF). Prepare a baking sheet with parchment paper.
Cut the tortillas into triangles and spray some oil over them. Season them with salt and pepper. Bake for 10 minutes, or until crunchy.
Heat a non-stick skillet to medium-high and add the beef. Cook until browned, breaking it frequently until no more lumps remain.
Add the onion, garlic, and taco seasoning, and cook for a few more minutes.
Grease a baking dish with cooking spray and transfer the meat mixture. Top with the tortillas, tomato, red onion, olives and black beans. Finish with a thick layer of cheese and bring to the oven. Cook until bubbly, around 12 minutes.
Serve with spring onions and cilantro.
