Peel the potatoes, cut into large chunks and boil in water until soft.
Preheat the oven to 200 C / 180 C fan / Gas 6.
While potatoes are boiling fry the minced beef in oil until browned. Season well with salt and pepper to personal taste. When browned add the shallot, turn down heat and simmer until softened.
Drain the potatoes and mash them with butter and milk. Add milk a little at a time, you don't want sloppy spuds!). Add salt and pepper whilst mashing then set aside.
In a jug mix the stock with garlic, tomato puree, paprika, thyme and Worcestershire sauce. Stir well.
Add the stock mixture to the minced beef and leave to simmer until some of the liquid has evaporated. You don't want lots of liquid at the end of the simmer, but don't let it be too dry. You should have about 3 tablespoons extra gravy.
Pour the meat mixture into an ovenproof rectangular glass dish (mine is 5 cm / 2 1/2 in deep) then spread the mash over the top.
Sprinkle over the grated cheddar, then thinly slice your tomato and place in a row down the middle of the pie. Sprinkle 1/2 teaspoon blue cheese on top of each tomato slice.
Bake in the centre of the preheated oven until lightly browned and bubbly, about 35 to 40 minutes. Serve the extra gravy and cavolo cabbage on the side.