Saute the onion, mushrooms and garlic in a little bit of water until all are soft.
Add in the drained beans, briefly cook to dry and then mash into the mushroom mixture.
Mix together the herbs, egg, cheese, breadcrumbs and flour and then add this to the mushroom mixture.
Roll the mixture into small balls and place on a lightly oiled baking tray and place in the fridge for around half an hour or until ready to cook.
Meanwhile, make the tomato sauce by sauteing the onion, garlic, red pepper, mushrooms and tomatoes (adding one by one in that order).
Add in the tomato puree, passata (or tinned tomatoes) and herbs and continue to cook through gently whilst you bake the balls, adding the spinach at the end of cooking to wilt.
When ready, heat the oven to around 180oC and place the tray of balls into the oven for around 30 minutes until firm and slightly crispy.
Serve with a side of your favourite greens veggies.