Yes, I have done Shepard's pie, Lise. I don't know if I was doing it correctly but here is what I do.
Take finely chopped veggies and stir fry. Take veggies like onions, green peas, leeks, carrots, celery, peppers, etc. Whatever you have an feel like having.
Mix these in with the ground beef.
Then, boil some potatoes and mash them. I saw on the cooking channel that sour cream added to mashed potatoes is a secret. Then, in a glass rectangle dish, (don't remember the size), add your beef with veggies and then spread the mashed potatoes on top.
Then, let it grill/bake slowly in the oven (all your food is cooked at this time, it just needs to mould together) When you see that the top of the potatoes is of brown color, then you're good to go.