Preheat the oven to 140ºC conventional bake.
Heat a little oil in a large pan over a high heat. Add the beef in batches and brown all over, then transfer to a casserole dish. Add the red wine to the pan; let it bubble rapidly for 30 seconds and pour over the meat.
Return the pan to a medium heat and add a dash more oil with the onion, garlic and leek and cook, stirring for 5 minutes. Add the mushrooms and cook for another 5 minutes. Add the stock, tomato paste, mustard, bay leaves and cornflour mixture. Stir to combine then pour over the meat in the casserole dish and stir. Cover and bake in the oven for 2.5 - 3 hours. Cool while your prepare the potatoes (remove the bay leaves).
Increase the oven temperature to 200°C conventional.
Place the potatoes in a large pot of cold water. Bring to a simmer and cook for 15-20 minutes or until tender. Drain and replace over a low heat for a minute to remove excess moisture. Mash briefly.
Stir the butter through and season to taste. Arrange spoonfuls on top of the meat mixture to cover. Toss the breadcrumbs in a dash of oil and scatter over the potato with the cheese. Bake in the oven for 15 minutes until golden on top (you can grill for the last few minutes).
Serve with seasonal vegetables.
Serving size: 4-5 Recipe courtesy of www.recipes.co.nz