Cook potatoes until tender. Drain and mash. If desired, whip with butter and milk.
Spread about half the potatoes in a round 2 litre casserole.
Mix chicken, soup and vegetables. Spread over potato layer.
Top with remaining potatoes.
Bake at 350 until heated through, about 30 minutes.
We like all things cheesy, so I usually put one cup grated cheese on top of the chicken layer, before the top layer of potatoes.
You can substitute an equal amount of chicken gravy for the soup.
This reheats very well in the microwave. In fact, sometimes I assemble it and put it in the fridge for the next night. Then I don't bother putting it in the oven at all, I just scoop out bowls full and zap them.