Heat the oil in a large saucepan. Add the onion and cook for 2 minutes until soft. Add the turkey mince and brown for 5 minutes, breaking it up with a wooden spoon as it cooks. Add the courgette and cook for 2 minutes.
Add the mixed beans and chopped tomatoes and bring to a simmer. Reduce the heat, cover and cook gently for 15 minutes, stirring occasionally.
Put the tortilla chips on a large serving platter (or divide between 4 plates), spoon over the chilli, then scatter over the Cheddar and spring onions. Serve immediately.
Cook's tip: make your food go further by adding 500g of chopped closed cup mushrooms with the courgette, and using an extra carton of chopped tomatoes. This will make enough chilli for two meals. You can freeze the extra batch for up to 1 month: just defrost overnight in the fridge before reheating.