Mushroom Filling

• 100 ml (3½ fl oz) olive oil
• 2 brown onions, thinly sliced

Heat half the oil in a saucepan over medium heat. Add the onion and garlic and cook for 10 minutes or until the onion is translucent. Add the saffron and cook for 10 minutes or until the onion is softened. Keep warm.

Meanwhile, dice the mushrooms into 1 cm (