As much as I love the luxurious creaminess of full fat potato gratins, I love this cream-less Julia Child recipe which gets its fat from cheese along with extra flavor from herbs and onions about as much. It's a staple in my repertoire, and I'm making it today for a dinner party. Since I had the recipe out, thought I'd share.
2.5 pounds boiling potatoes ('boiling' is her word, I prefer russets)
About 2 cups vegetable or meat broth (I prefer chicken)*
1 large clove of garlic, minced
1 whole medium onion, thinly sliced and softened in 2 T butter
a few pinches of thyme
1.5 cups grated gruyere type cheese (I like the creaminess of Jarlsberg)
Soften the onions, then add the garlic. Thinly slice potatoes. Fill a greased baking dish with a layer each of onions, potatoes and cheese, then repeat ending with a layer of cheese. Pour in the stock to come halfway up and bake for about 40 minutes in the lower middle level of a preheated 425 F oven. She recommends you suck up the juices periodically with a bulb baster or spoon and baste the top of the potatoes several times. I have found it makes more sense to loosely cover the dish with foil for the first 25 minutes of cooking, baste once, remove foil and move the dish up in the oven where it will brown better during the final cook--about 20 minutes.
This makes a wonderful vegetarian main course, it's very complete. A little steamed broccolini or rapini on the side and you've got something great on the plate. I'll be adding truffles to today's gratin.