Forestier is a French term that means “of the forest,” but describes just about anything with mushrooms. If you love potatoes and mushrooms, you’ll love this dish.
This recipe is my version of a classic potato gratin, because the potatoes cook in cream. The addition of the mushrooms make it a bit “meatier.” It’s fabulous as a hearty side dish to a filet of beef or salmon steak, or, served with a salad for a fabulous lunch. I hope you like it!
4 ounces dried mushrooms
1 stick butter
8 ounces fresh mushrooms, sliced
3/4 teaspoon dried thyme
1/2 teaspoon salt
3 pounds red waxy potatoes
2 1/2 cups cream
4-5 ounces Parmesan*, grated
Place the dried mushrooms in a medium bowl and cover them with boiling water. Let them sit for about 30 minutes.
Meanwhile, Place about 1/2 stick of butter in a large skillet over medium-high heat. When it’s melted, add the fresh mushrooms and sauté them for about 5-6 minutes. Add the thyme, salt, and a few grindings of black pepper. Remove them with a slotted spoon and place them in a colander that’s on top of a medium-sized bowl; set the skillet aside.
When the dried mushrooms have hydrated, remove them from the water and using paper towels, blot them dry as best as possible. Coarsely chop them up.
Add the other 1/2 stick of butter and heat it in the same skillet over medium-high heat. Sauté these mushrooms for about 5-6 minutes. Add them to the others in the colander.
Preheat the oven to 400 degrees. Choose a fairly shallow baking dish for these potatoes, but it should be deep enough to incorporate a couple layers of potato slices, a layer of the mushrooms, and then a couple more layers of potato slices, as in the very bottom photo. The fewer slices makes for faster cooking, and I just like the higher ratio of potato to mushrooms like I make it. And, it looks pretty!
Once the mushrooms are finished “weeping,” get the bowl from underneath the colander, and pour all of the cream in the bowl.
Get out your mandoline (be careful!) and slice all of the potatoes thinly, but not paper thin. One eighth of an inch is fine. It doesn’t matter if the potatoes are sliced crosswise or lengthwise. Just don’t slice your fingers.
As you slice the potatoes, place them in the bowl of cream, and make sure each slice is coated all over. Continue with the remaining potatoes.
To start preparing the Potatoes Forestier, first place your baking dish on a jelly-roll pan to catch the cream that will inevitably bubble up. Place a slice of creamy potato on the bottom of the baking dish, and cover the whole bottom with slices, repeating the process again. Then top with all of the sautéed mushrooms. As with the first potato layers, complete the dish using the remaining potato slices.
Pour the remaining cream into the gaps between the potato slices. Sprinkle the grated Parmesan onto the potatoes, but leave a border so that the pretty potatoes show.
Bake the potatoes for about 45 minutes. To test them, you should be able to insert a knife or cake tester easily. The potatoes will also be browned.
Let the potatoes cool, then slice and serve. Or, chill them after they’ve completely cooled, and reheat the next day.
* If you prefer, use the more classic Gruyère for this potato dish.
note: Any kind of mushrooms will work in this dish, from domestic to wild. I prefer the mixture of fresh and dried mushrooms, but you can use 1 pound of sliced fresh mushrooms if you prefer.
another note: If you prefer, toss a handful of prosciutto dice in with the mushrooms!