400g/14oz broccoli, stalk chopped, florets cut into 2cm/¾in pieces
1 large garlic clove, crushed
1 leek, roughly chopped
1 brown onion, roughly chopped
100g/3½oz potato, peeled and diced
1 bay leaf
salt and freshly ground black pepper
1 tbsp olive oil
1 litre/1¾ pints vegetable stock (or light chicken stock)
25g/1oz butter
150g/5½oz mature cheddar, grated
100g/3½oz crumbly blue cheese (such as Stilton)
150ml/5fl oz full-fat milk
sourdough croûtons