Heat oil in a pan and add the onions, mushrooms and chillies. Cook until soft add salt and pepper to taste. When soft, stuff the halved peppers with the mixture.
3.
Cut mozzarella cheese into thin slices and place on top of the peppers. Place on a lightly oiled baking tray. Drizzle olive oil over stuffed peppers and place in the oven. Cook until cheese is golden.
Tip
Use fresh mozzarella for best results. For a vegan option, use breadcrumbs as a topping instead of cheese.