For the tarts:
First make the caramelised onions by spray a large frying pan with cooking spray and fry the onion slices, adding the sugar about halfway through.
Preheat the oven to 170°c, and make the filling by mixing together the egg, onion and cheddar and set aside.
Layer filo into tartlet tins, spraying each layer with light cooking spray. Fill the tartlet’s delicate filo layers with the eggy, cheesy mix.
Bake at 170°c for 30 mins. These tasty tarts can be enjoyed hot or cold.
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