Heat oven to 180C/160C fan/gas 4. Heat the oil in a frying pan and cook the onion and garlic for 5 mins. Stir in the fajita seasoning and cook for 1 min more before adding the kidney beans, shredded chicken and sweetcorn.
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 mins until golden and bubbling.