I don't know where the name comes from, but the dish is really called Jansson's Temptation. And it's delicious. One of my faves from the christmas foods, but it's also served at Easter or as a late night snack. It's very salty but still sweet - Swedish anchovies are cured in a sweet brine and not very fishy. My favorite way to eat this is to pair it with meatballs. Yum!
4-5 medium potatoes, roughly grated
1 small can of Swedish flat anchovies (125 g)
1 large onion, thinly sliced
300 ml of heavy cream
Preheat the oven to 225°C. Mix the potatoes with the onions, and add a little bit of salt and pepper. Put half of the mix in a buttered oven proof dish. Top with all of the anchovies. Add the rest of the potatoes and onions. Drizzle over half of the cream, and put in the oven. After about twenty minutes, add the rest of the cream. Bake until it has some color - about twenty more minutes, so 40 minutes in total.