OK, ok. This one takes some amount of patience if you don't have one of those slicey-dicey machines (also known as a mandolin). At least I'm being honest!!! I had to cut all. of. these. potatoes. I almost shaved off my fingernail in the process, too. Well -- I did shave off part of my fingernail. So, please, be advised, while ABSOLUTELY DELICIOUS, get a mandolin.
White Truffle Potatoes au Gratin
Serves 8-12; Cooking Time: 2 hours
- 4 pounds russet potatoes, sliced with a handy-dandy slicer-machine (mandolin) or cut meticulously with a sharp knife for five hundred hours. (I'm bitter.)
- 3 ounces gruyere, your preference (smoked will go really nice with the truffle oil)
- 2 ounces parmesan
- 2 cups heavy cream
- 2 cloves of garlic, minced
- 5-6 sprigs of thyme, roughly chopped
- 1 Tbs truffle oil
- 2 Tbs butter
- Salt and pepper to taste
Preheat your oven to 400 degrees. Ok, so. Start by prepping your potatoes. With a mandolin. Please. This process will take you maybe 5 minutes max if you go this route. If you choose to slice every single potato (like I did), you will be a miserable wretch who will resent every bite of your delicious gratin. Slice them about an 1/8 inch thick. As thin as humanly possible.
In a small bowl, combine the cheeses. They should be shredded. Take about a third of the cheeses and put them in a large bowl. In this cheese bowl, mix together the cream, minced garlic, thyme, truffle oil, and salt and pepper to taste. Next, add your potato slices to the cream mixture and make sure they are all coated evenly. Yes, use your hands.
Grease a relatively large casserole dish with butter. Now the first time I did this (pictures) I lay them flat, horizontally. I found this to bring about less of a nice crunch on the top and more uneven cooking which yielded varying potato textures. The way I'm going to tell you to do it (a la J. Kenji Lopez-Alt's technique in The Food Lab) is to stack them vertically, in rows. While it requires just a bit more leg work, I swear the result is that much better.
Once your potatoes are stacked, pour whatever cream is leftover in the casserole dish until it comes up halfway to the potato slices. Cover dish tightly with foil and put in the oven for thirty minutes. Remove foil and cook for another thirty minutes, until the top is golden brown and delicious. Gently remove from oven and add the remaining cheese on top, along with some more cracked black pepper. You can also drizzle more truffle oil on top, if you're all about it. Cook for its last thirty minutes!
Remove from oven and let sit for a few minutes. Serve immediately! Tastes even better the next day, for leftovers!