Potato Gratin - German Kartoffelgratin

Posting for ZWT 6. Another recipe I found on About.com for German Foods. Here is the description: If you have ever eagerly anticipated the potato gratin at a restaurant or a friend's house only to be confronted with an angry mass of gray, underdone potatoes, this is a recipe for you. We potato gratin lovers have to band together to teach the world about the true meaning of potatoes cooked in cream and salt. They have to bake for over an hour, the cream must be abundant, the potatoes must be layered horizontally, and fresh herbs and pepper only, please.

• Ready In: 1 hr 50 mins
• Serves: 8-10

Ingredients

• 6  lbs potatoes (Russet or Yukon Gold are fine)
• 2 -3  cups heavy cream
•  salt & freshly ground black pepper
• 1 -2  cup cheese, grated (such as Emmentaler or Gruyere)
•  marjoram (optional) or   other herbs (optional)
•  onion, discouraged (I personally love onions with potatoes and would say optional)

Directions

1. For this amount of gratin, a 9 inch by 13 inch, buttered pan is a good choice. Peel the potatoes and slice by hand 1/8 inch thick. Do not do this in the food processor, since they slice too thin.
2. Line up the potatoes in rows across the back of the pan. Alternate slices from different potatoes in the same row, and make sure each slice has been separated from its sister slice (make sure all slices have broken contact with each other, otherwise they cannot absorb the cream). See image.
3. When the pan is getting full, you can push the rows back to a vertical position and fit more potatoes into the pan.
4. Fill the pan one half to two thirds with cream, pouring over the potatoes. Salt (I start with one teaspoon) and pepper. You might want to sprinkle a little marjoram on it, fresh or dried, too.
5. Bake in a heated oven (375°F) for one hour, then sprinkle the cheese on top and bake until the potatoes are very tender when poked with a fork.
6. Notes: The baking time varies with the type of potato, elevation where you live and how hot your oven really is. It has always taken about 90 minutes for me, yet so many cookbooks say 45 minutes, it burns me up.
7. This is not a low-fat food, but it does not work very well with milk, so maybe you will make it once or twice a year as a special treat. You may also leave off the cheese, if you want.
8. You may cover the casserole with foil in the middle of baking time if it is becoming too brown. Remove it before you add the cheese.