Pre heat the oven to 190C/ 170 fan Gas 5.
Par boil the diced potato in salted water until it is soft but not completely cooked. Drain and leave to cool.
In a large bowl, gently mix together the salmon, cooked potatoes, spring onions, peas, parsley or dill, creme fraiche and milk.
Season with salt and pepper and pour into a medium sized oven proof dish.
Mix the breadcrumbs and cheese together and sprinkle across the top to cover the fish mixture.
Cook in the pre heated oven for 20 minutes until piping hot and the topping is golden brown.
If you want to serve some extra vegetables, broccoli works well as a side.