Janssons frestelse is a Swedish creamy potato casserole with anchovies and onions. Swedes love to eat this for Christmas, but it's also throughout the year as well.
Butter a large oven safe casserole dish. Preheat oven to 435°F (225°C).
Slice the onions and sauté them in just a tiny bit of butter or oil on low/medium heat for ten minutes. They should become clear but not brown.
Peel the potatoes and cut them into strips (like french fries). Layer the potatoes, onions, and anchovies/sprats in the casserole dish (start and end with potatoes).
Mix the cream and anchovy broth together and pour half of it over the casserole. Add small pads of butter to the top of the casserole and sprinkle with bread crumbs.
Bake in the middle of the oven for 25-30 minutes. Remove the casserole from the oven and pour the rest of the cream mixture along the edges of the dish. Bake for another 10-15 minutes until the potatoes are soft and the casserole is a deep golden brown.