1.In a large frying pan, heat the oil until hot, add half the mince, season with pepper and fry until well browned. With a slotted spoon, remove the meat from the pan and place in a metal colander to allow the excess fat to drain. Repeat with the second batch of mince and place in the colander.
2.Add the onion and carrot to the pan with the thyme and garlic and a knob of butter, and cook until soft and translucent. Add the meat and tomato purée, then sprinkle over the flour. Cook stirring constantly for 2-3 minutes to cook the flour.
3.Add the red wine and Worcestershire sauce and cook until the liquid has reduced to half the original volume. Add the chicken stock, bring back to the boil, then simmer for 30-40 minutes. The mixture should be thick and glossy. Allow to cool, then check the seasoning.
4.Mash the potato until creamy and smooth or pass through a Mouli or potato-ricer. Put into a medium-sized mixing bowl. Place the milk and butter into a small pan and heat until the butter is melted and the milk is about to boil. Pour over the potatoes and beat well, adding the egg yolks and seasoning with salt and white pepper. Add parmesan cheese
5.Put the mince into a large baking dish, then top with the creamed potato. Sprinkle on parmesan cheese and use a fork to rough up the top.
6.Place in a preheated oven at 400°F for 30 minutes or until bubbling and golden brown in color.