Peel the potatoes, cut them into cubes, then put them in a pot of cold water. Add the bay leaf, bring to the boil and cook for 15 minutes or until tender.
Meanwhile, chop the onion, garlic, carrot and celery.
Heat the oil in a large pot over low heat, then gently sauté the chopped vegetables for about 10 minutes. Stir in the herb mix and the mince. Stir for 3-5 minutes until the meat changes colour.
Stir in the tomato purée and wine, then after a couple of minutes add the tinned tomatoes and enough water to just cover everything.
Add the stock pot and bay leaf.
Bring to the boil, cover and simmer for 25 minutes until the sauce has thickened. Add the peas and cook for another 5 minutes. Turn off the heat and stir in the parsley.
When the potatoes are ready, drain them and discard the bay leaf. Put the potatoes back in the pot and add the gorgonzola and butter, then season with salt and pepper. Mash the potatoes until get a creamy mash. Add more butter or some milk if required - the mash should be thick. Keep warm under a lid.
Preheat the oven to medium grill setting.
Spoon the mince stew into a deep baking dish. Top with the mash, then make rough lines on the top, using a fork. Scatter some Parmesan on top, if used, then put the dish in the oven for 5-10 minutes, until the top becomes brown and crispy.
Serve warm.