Heat the low calorie cooking spray in a pan. Cook onion and garlic until soft.
Add peppers, mushrooms, bay leaf and chilli/red pepper flakes if you're using them. Stir for 2 minutes.
Cover and cook for around 5 minutes.
Add the chopped parsley, and season to taste.
If you're using cheese, after 15 minutes cover with grated cheese and bake until golden brown. Otherwise just leave it cooking for another 10 minutes.
Serve straight out of the oven with white rice.