TO FINISH 1 red onion, sliced Preheat the oven to 230°C. Grease 2 baking sheets with non-stick spray.
1 FILLING Heat the oil in a large pan and fry the onions until soft. Add the spinach and stir-fry until wilted and all the moisture has evaporated. Transfer the spinach mixture to a mixing bowl and leave to cool.
2 Mix the mozzarella cheese into the spinach. Season with lemon juice, salt and freshly ground pepper.