Decadent Porcini-Potato Gratin
It’s funny how the word “potluck” takes on different connotations at different points in your life.
In my formative years, potlucks were part of PTA events and end-of-the-year high school club banquets. In fact, I think the first recipe I ever made up on the fly with whatever was in the kitchen was for a high school drama club banquet. My best friend, Beth, and I called it The Chicken Stuff and I know there was chicken and celery and mushrooms, obscene amounts of cheese and possibly Stove Top stuffing on the bottom (I am 95 percent sure there is a photo somewhere). My mother was horrified. I, being 17, was triumphant at her horror, even more so when the casserole dish came home empty. On a buffet line that surely included ample creamed chipped beef, baked beans and Jell-O salad, at least it was something different. Were I able to recreate it, I am certain it would become an instant New Classic in the Midwest.
Later, in college, potluck meant something else, something that featured many items that could be made in the microwave or using boiling water from illicit hot pots or just stirred together and chilled. I did a lot of stirring together of exotic-seeming dips in those days, sometimes some mashing with the back of a fork. There was also one mini-fridge concocted no-bake cheesecake and one ill-advised “raspberry rice salad,” both of which for Daily Kent Stater events (Reporters really will eat anything. Especially college reporters…).
Then there were the Lean Years. The Just Starting Out Years. That’s when “potluck” became integral to survival, conjuring visions of long tables filled with an amount and a variety of foods you couldn’t possibly afford to make in a month on your urban singleton grocery budget. In DC, back before being a “foodie” was a “thing,” I don’t even think we called them potlucks. It was just my young urban family — all big food fans, of course — trying to impress each other with our mad cooking skills without breaking the bank.
The first time I encountered this recipe, it was a version from a now-forgotten magazine that served eight and required more ingredients, including, I think, some kind of homemade breadcrumb set up in addition to the cheese for the top layer. I am sure I followed it faithfully, but there are just two things I actually remember from making it the first time: 1) trying to maintain my composure at the Eastern Market cheesemonger when he gave me the total for the Gruyere and 2) that it was a total hit. I fiddled with the recipe after that, not too much. But I still rarely made it, even a few raises later when I could afford the cheese, because of its sheer volume. Anything that serves eight has little business in a single girl’s recipe arsenal. Or even a married girl’s! It was a few more years before I thought to shrink it down to a manageable size. And now here we are, with decadent potatoes for two.
1/2 oz. dried porcini mushrooms
1 cup hot water
1 Tablespoon unsalted butter
2 medium shallots, finely chopped
1 garlic clove, minced
1 teaspoon fresh thyme, chopped (or 1/2 teaspoon dried)
1/2 cup heavy cream
1/2 teaspoon kosher salt
1 1/2 to 2 lbs. Russet potatoes, peeled
1 1/4 cup (about 2 oz., pre-grated) grated Gruyere, divided
Heat oven to 400 F and butter a shallow gratin dish. Place dried mushrooms in a coffee filter-lined bowl. Pour hot water over mushrooms and let stand 15 minutes, or until mushrooms are soft. Remove mushrooms, gently squeezing out the water and finely chop. Reserve 3/4 cup of soaking liquid (that should be about all that’s left anyway).
Melt butter in small pan over medium heat. Add garlic and shallots, cook until softened, about 2 minutes. Add mushrooms, thyme and reserved soaking liquid and boil until the liquid is reduced by half. Remove from heat and stir in cream, salt and 1 cup cheese.
Thinly slice potatoes with a mandolin or V slicer. Layer potatoes in gratin dish, overlapping slightly. Spoon on some mushroom mixture and spread thinly, repeating after each layer. After the last addition of mushroom mixture, add a final later of potatoes and top with the remaining 1/4 cup cheese.
Bake 30 minutes or until browned, bubbly all over and potatoes are tender.
Note: Gratin can be made up to eight hours ahead of time, covered and refrigerated. Reheat, covered, at 350 for 30 minutes or until hot.