Jansson's Temptation (Swedish Potato and Anchovy Casserole)

I found this on another website researching Swedish recipes. I love to make it and not tell people it has anchovies in it until after they rave about how good it is. The anchovies melt into it to make a sauce. It has such a yummy flavor! Here is a quote from the recipe: "Jansson's Temptation is a classic Swedish dish traditionally served before guests leave to ensure that during their cold journey home they have something warm inside them."

• Ready In: 1 hr 25 mins
• Serves: 10

Ingredients

• 2 -3  large onions, sliced
• 3  tablespoons unsalted butter
• 6  russet baking potatoes, peeled and sliced thin lengthwise
• 1 (2 ounce) can anchovy fillets, drained, reserving the oil and chopped
• 1 1⁄2 cups heavy cream
•  salt and pepper

Directions

1. In a large skillet cook the onions in 2 tbsp of the butter over moderate heat, stirring occasionally, until they are golden.
2. Preheat oven to 400.
3. In a buttered 2 1/2- 3 quart shallow baking dish (13x9 works well), layer 1/3 of the potatoes, 1/2 of the onions, 1/2 of the chopped anchovies, salt and pepper to taste, 1/3 potatoes, 1/2 onions, 1/2 of the chopped anchovies, salt and pepper to taste, last third of potatoes.
4. Drizzle the top of potatoes with the reserved oil from the anchovy can (about 2 tbsp.) and dot them with the remaining 1 tbsp of butter cut into bits.
5. Bake the casserole on the middle rack for 10 minutes.
6. Pour 3/4 cup of the cream over the potatoes and bake the casserole for 20 minutes more.
7. Pour the remaining cream over the casserole, reduce heat to 300, and bake for 30 minutes more or until the potatoes are tender.
8. Great served with anything that goes well with a potato side dish.