I'm pretty sure someone will have a much tastier recipe, but my pie consists of:
Cooking stewing steak in the slow cooker with onions and carrots (I find the meat is much more tender done in the SC)
When it's ready, I put it in a dish, cover with puff pasty - remember to make a small hole in the top to let steam out - and chuck in the over for however long it takes the pastry to cook - usually half an hou or so.
I serve with peas and mashed potato with wholegrain mustard stirred through it.