Bridget Jones's Shepherd's Pie
Preheat the oven to 180 C.
Add the chopped tomatoes and pour the stock mixture.
For the mash, boil the potatoes, then drain them in a sieve and place into a clean bowl.
Add the milk, butter and egg yolk, and mash together.
Put the dish into the oven and cook until the surface is bubbling and golden-brown.