Mushroom Risotto

50g dried porcini mushrooms 1 vegetable stock cube 2 tbsp olive oil 1 onion, finely chopped 2 garlic cloves, finely chopped 250g pack chestnut mushrooms, chopped 300g risotto rice, such as arborio 1 x 175ml glass white wine 25g butter handful parsley leaves, chopped 50g parmesan or Grana Padano, freshly grated