Slice potatoes and onions. Mix eggs, milk, cream, water, salt and pepper to an egg mixture.
Turn boiled potatoes, salmon, onions and dill into a greased oven dish. Pour on the egg mixture. Plan the butter with a cheese grater and place on top.
Bake in the middle of the oven until the egg has set, about 40 minutes at 200 degrees. Serve with a salad.