My version is based on the splendid Hugh Fearnley Whittingstall's version in his River Cottage Meat Book...though I am not convinced that he would acknowledge his offspring.
Ingredients for "an enormous Shepherd's pie".
500 g minced beef.
A splash of olive oil.
2 onions, chopped.
2 carrots, finely chopped.
3 sticks of celery, finely chopped.
1 leek, finely chopped.
1/2 pint stock.
1/2 glass red wine.
1 tablespoon or dollop of tomato ketchup (I am keen on Tiptrees although I accept there is nothing wrong with the ingredients in Heinz).
Two dashes of Worcester Sauce.
About a kilo of mashed potato - mashed with butter and milk.
Freshly ground black pepper.
I suggest you use a frying pan to fry the mince, a large saucepan to boil the potatoes and a larger saucepan for everything else including, later, the mince. You'll also need a suitable pie dish. Plus a potato peeler, a sharp knife (I recommend a serrated kitchen devil), a chopping board, a wooden spoon and a colander. It's worth laying out all the ingredients and utensils in advance.
Ok. Heat the oil in the largest saucepan and add the chopped onion. Allow the onion to cook very gently. Unlike HFW, I recommend against allowing it to brown. One step nearer to bitterness. Next, add the carrot and the leek. Keep going, very gently, stirring every so often.
Now, fry the mince on a relatively high heat, encouraging it not to steam or to burn but to brown. When it's cooked through, add it to the vegetables and mix everything together thoroughly. Add the ketchup and the Worcester sauce, followed by the wine and the stock, in swift succession. Again, mix it all together well. Turn the heat to its lowest setting and let the whole thing cook for around half an hour although it is forgiving and will allow you longer. Taste, add salt and pepper if needed and additional Worcester sauce and ketchup, if needed. But this is not a tomato based sauce. It is the mince and vegetables that should sing. You can also add a little water or wine if it's in danger of drying up...but you don't want excessive amounts of liquid. Think casserole rather than soup. Stir every so often.
While things are cooking, peel, chop and boil the potatoes. Mash them with butter and milk: not too much though.
Once the mince and vegetables are cooked, tip them from the saucepan into a pie dish. Then put the mashed potato on top. Several dollops plonked unceremoniously on to different parts of the pie dish...and then spread it as evenly as you can without being precious about it. Use a fork to make patterns which will brown nicely. Don't worry if the gravy at any point slops on to the potato. I think the reason this is intuitively displeasing is because it feels like planting muddy footprints on to a virgin field of snow. Once again, this dish is very forgiving. Spilt gravy will simply cause the potato to brown better. But do try to seal the edges.
If you're wanting to eat this in about half an hour, put it straight into a pre heated oven at about 200 degrees and cook for around twenty five minutes. Or, if you want to eat it later, say the next day, put it into the fridge. It will then take about 40 - 45 minutes to cook from cold. Keep an eye on it while it's in the oven. You are aiming for golden brown rather than burnt brown. When you take it out of the oven, it should be bubbling up at the sides however well you sealed it and this is a good thing. Eat.
Bolst's mango pickle goes particularly well with this as does lemon pickle. Others like Worcester sauce, ketchup, mustard or other things. My view is that in the case of Shepherd's pie, it's particularly important to cater for everyone's different tastes, condiment wise. The following idea comes from Nigel Slater. Put all relevant jars and bottles on the table including those rather suspect jars with wax paper containing mustard with honey or chilli jam that someone gave you as a present ages ago. Someone else will love it.