Friday, January 13, 2012

Mushroom and Potato Gratin

by Sheila Connolly

I fell in love last week.  With a mushroom.

Here's why. Last October the Wegman's supermarket chain opened its first New England store.  As its location is more than an hour north of where I live, I didn't have an opportunity to visit until last week, when I in the area.  As soon as I walked in I realized that I should have allowed a full day to explore it—it's huge!  138,000 square feet (says the press release), 600 employees.  Inside it feels like it's as big as a football field, or maybe two. [I just checked:  a football field is 57,600sf, so this Wegman's is the size of 2.4 football fields.]

But this store is not all about size.  Each department carries an incredible range of products, from bulk flats to high-end specialty items.  I wandered along the refrigerated ranks of the meat department, and spotted wild boar (genuine feral pigs!), venison, whole rabbit (minus the head and fur, of course), a dozen kinds of bacon...  I resisted, although I did stock up on four kinds of bread. And cheese to go with it.

But my real downfall was the produce department.  The fruits and vegetables area was well stocked but not particular unusual—until I encountered The Mushroom.  The picture barely does it justice (I should have stuck my hand in for scale), but it's one single mushroom—a Hen of the Woods, to be precise. 

If you don't recognize it, it's not surprising.  I've never seen one in a store before, although I have had them occasionally from local farmers markets.  Grifola frondosa – also known as ram's head, sheep's head, or dancing butterfly mushroom.  Widely found in Eastern Pennsylvania (how did I miss that?), growing at the base of dying oaks and other hardwoods.  Mild flavored, and the whole thing, including the stem, is edible.  (As an aside, it's also under study in AIDS research and may contain an anti-tumor substance.)

So I promptly bought the whole 1.2 pounds treasure and brought it home and contemplated it.  What to do?  Soup? Nope, I did soup last week.  Some kind of side dish?  Okay, but what?  I knew I wanted to involve cream, and maybe some garlic.  I started wading through my cookbooks, but I couldn't find anything that seemed right.  The closest were variations of a potato-mushroom casserole, in Cooking with Shelburne Farms (by Melissa Pasanen and Rick Gencarelli) and the Chez Panisse Cookbook (by Alice Waters)—so I combined them to get what I was looking for. 

Mushroom-Potato Gratin

1 ½ pounds potatoes, sliced thin (I happened to have a batch of new potatoes on hand so I used those, unpeeled.  If you're using larger, older potatoes you should peel them.)

1 or 2 cloves garlic, minced
3 Tblsp butter
1 pound mushrooms (since you're not likely to find a giant mushroom at your supermarket, you can use a mix of whatever flavorful types you have)
1½ cups heavy cream or half and half
¾ cup grated cheddar (I used Gruyere)

Additional salt and pepper

Preheat the oven to 375 degrees.  Butter a 1½-2 quart shallow casserole dish.

Coarsely chop the mushrooms.  Melt the butter and briefly sauté the garlic over medium heat, until it is softened but not browned.  Add the mushrooms and sauté, turning frequently, until they begin to release their juices, about 5-6 minutes.

Arrange a layer of sliced potatoes (it doesn't have to be neat) on the bottom of the baking dish, and sprinkle with salt and pepper.  Spread a layer of the cooked mushrooms over the potatoes.  Continue layering, ending with a layer of potatoes.

Pour the cream over the potato-mushroom layers (it will not cover the top layer, but that's all right).  Sprinkle the top with salt and pepper, then spread the grated or shredded cheese on top.

Bake in the preheated oven for 65-75 minutes, or until the sauce is bubbly and the cheese topping is golden brown. (You might want to put a baking sheet under the casserole in case it bubbles over.) Remove from the oven and let it sit for 5-10 minutes before serving.

Serves 3 to 4 people as a main dish (especially if you include a salad or vegetable on the side) or 6 to 8 as a side dish.


  1. Gotta love Wegman's! I am a bit envious though...the Wegman's around me aren't THAT huge and amazing. Still wonderful though.

  2. Your Wegman's "Hen of the Woods" find looks like something out of the Black Forest. Inspiring to be sure (but a little scary, too). Perfect for a Friday the 13th. Gratins are always work but always worth it, and this looks delicious enough to send me mushroom hunting. Just came back from Chinatown, too. Dang, should have paid more attention to those 'shrooms.

    Thanks for sharing and have a happy Friday the 13th! Bwa-ha-haa!

  3. The recipe looks delicious, but I'm afraid I wouldn't have had the nerve to buy that...thing!

  4. A butterfly mushroom! Who knew? It looks so exotic! What a fun post. Thanks, Sheila.

    Oooh, Friday the 13th. I was born on a Friday the 13th. It's my day. Yay!


  5. I have seen those mushrooms at the base of trees. Not sure I would have the nerve to eat one. Every spring, huge mushroom globes grow here. They're white. I call them puffballs, but I'm sure they must have a proper name. Imagine my surprise when I saw that one enterprising person was selling them by the slice at the farmer's market. No, I don't think I'll be trying them . . . .

    This dish is fantastic, though. Gorgeous, and I bet it tasted wonderful.

    ~ Krista

  6. I have never collected mushrooms in the wild (although I know people who do--including in Golden Gate Park in San Francisco, but those aren't the eating kind...). There are so many varieties out there!

    I lived for years in Pennsylvania, and once my father took me to Joe's Restaurant in Reading, which led the way for locally harvested exotic mushrooms. It was a simple place but the food was memorable. Alas, they moved to the West Coast (traitors!). The owner has a couple of cookbooks out, which include recipes for puffballs, Krista. (He compares a puffball to slightly minty tofu.)

    My family certainly enjoyed the dish!

  7. Oh wow! Yum, yum, yum! I'm making this this weekend, because we LOVE potatoes, mushrooms, and cheese. This is like the flavor hat trick for us. :)

  8. I love mushroom and potatoes and cheese, so this recipe sounds fabulous! Thanks!