Heat oven to 180°C. Heat the oil in a frying pan and cook the onion and garlic for 5 minutes. Stir in the fajita seasoning and cook for 1 min more before adding the beans, chicken and corn.
Divide the mixture between the tortillas, sprinkle over half the cheese, then roll up and place into a baking dish. Sprinkle over the remaining cheese, then bake for 20-25 minutes until golden and bubbling.