Chicken and mushroom risotto

Name: Chicken and mushroom risotto
Ingredients: 2 tbsp olive oil; 350–400g/12–14oz skinless chicken breast fillets, cut into roughly 2cm/¾in chunks; 50g/1¾oz butter; 1 brown onion, finely chopped; 250g/9oz chestnut mushrooms, quartered; 2 garlic cloves, crushed; 1 bay leaf; 250g/9oz risotto rice, such as carnaroli or arborio; 150ml/5fl oz dry white wine; 950ml/1¾ pint hot chicken stock (fresh or made from 1½ chicken stock cubes); 75g/2¾oz Parmesan, finely grated; salt and freshly ground black pepper; freshly chopped parsley, to serve (optional)