Preheat the oven to 180C/gas 4. Heat the oil in a medium frying pan over a medium heat and fry the onions and garlic for 5 mins until soft. Add the beef, turn the heat up to high and continue to cook, stirring, until the beef has browned. Drain off any excess oil.

Stir in the taco seasoning and salsa, turn the heat back down to medium and cook for 5 mins. Stir in the beans and corn. Pour the mixture into a 13 x 9in baking dish or round pan, then top with the half the shredded cheese. Scatter the tortilla chips on top and cover with the remaining cheese. Bake for 20 mins, or until the cheese is melted and the casserole is bubbling. Serve with crema or sour cream, guacamole, jalapeños, coriander and pico de gallo.