Preheat oven to 200C

Peel potatoes, cut into small chunks and boil on hob for 20 mins until soft

Drain potatoes and mash potatoes with milk

Grate the cheese and mix into the mash along with the mayonnaise

Put mixture into an oven proof dish, garnish with tomato and sprinkle with cheese

Bake in oven for 20 mins until cheese has melted and serve!