I really, seriously don't want to sound like a smartarse, but shepherd's pie is made with lamb. You know, shepherd - sheep.
I believe your extremely-tasty-sounding dish might come under the Cottage pie monicker. I think I'll give it a go. Thanks, ripsaw
BTW, when I do a shepherd's pie I like to have lamb, onions frying, then add Heinz baked beans just before the mashed potato goes on and it goes into the oven. Yes, it's radical, but that's how my Granny did it. It was the only thing she could cook!