In our house, recipes often stem from my reading, and equally as much from misunderstanding (or from puns, but that’s for another day). These scalloped sweet potatoes and zucchini, simple and very satisfying, come from both those sources: a series of happy accidents. A couple weeks ago, I needed to make a dish for a potluck, and I had large amounts of sweet potatoes and zucchini cluttering up my counter. I had just been revisiting some books I hadn’t read in a while, including Jeffrey Steingarten’s It Must’ve Been Something I Ate. One of the essays in that book is a brief paean to a well-constructed gratin, followed by a cantankerous and exacting recipe for gratin dauphinois that almost matches the essay in length.
In my usual fashion, I ignored almost everything Steingarten wrote and used his basic proportions to put together a lovely layered casserole of sweet potatoes and zucchini, full of rich cream and milk and nutmeg, which came out nothing like a gratin dauphinois but which was very well received. As I was unpacking the small amount of leftovers, Jarod spied the soft orange flesh of the sweet potatoes and asked “Is that salmon?”
It wasn’t, but what an idea! It makes perfect sense: the bubbling cream recalls the white sauces often served with salmon; the sweet potatoes and the fish trade places, texturally, as the roots soften and the fish firms in the oven; the thin slices of zucchini, frilling a bit at their edges, are almost like the thin parchment wrapping of a fish served en papillote.
It was such a good idea that the very next day I went to the store and purchased a quarter-pound of smoked salmon to add in, as well as some dill. In they went, and the result was delightful. The small amount of salmon is worth the expense: in changing Steingarten’s original recipe, I had lost a bit of the savory depth that a proper gratin dauphinois takes on in cooking, which the salmon adds back. The end result is a very different dish from the one that inspired me, but it’s one that holds together and satisfies. Thank goodness for having many books on hand, and for serendipitous misunderstandings.
Scalloped sweet potatoes and zucchini with salmon
Soft sweet potato and zucchini, wrapped in a thick cream sauce, remind me of classic scalloped potatoes, yet the dairy is restrained enough that it doesn’t sit too heavily. The small amount of smoked salmon brings a rich savor that can make this into a main dish for lunch, but it would also be at home on a buffet as a vegetable side, with or without the salmon.
Adapted from Jeffrey Steingarten’s recipe for “Gratin Dauphinois” in It Must’ve Been Something I Ate.
4 Tbsp softened butter, divided
1 cup milk
1 large garlic clove, lightly crushed and peeled
1 tsp kosher salt
1/2 tsp ground black pepper
1/8 tsp ground nutmeg (about a dozen turns of a nutmeg grater, if you’ve got one)
1 1/2 lbs. sweet potatoes
1 1/2 lbs. zucchini
4 oz. smoked salmon, torn into small pieces
3 Tbsp finely chopped dill
1 c heavy cream
Preheat the oven to 425°F. Use 2 Tbsp of the butter to generously butter a 9 x 13 baking dish.
Combine the milk, garlic, salt, pepper, and nutmeg in a medium saucepan and heat over medium-high heat until bubbles appear around the edge of the pan. Set aside. (Be careful; if you bring the milk to a full boil, it’ll boil over, and it’s hell to clean up.)
Peel the sweet potatoes and slice 1/8″ thick. This is possible with a knife if you have good knife skills, but is much easier and faster with a mandoline slicer! Slice the zucchini into 1/8″ slices as well.
The idea now is to make a smooth, overlapping layer of sweet potatoes in the bottom of the baking dish. Make a line of sweet potato slices down one of the short sides of the dish, overlapping each slice over the last one. Make another line of slices next to it, overlapping the whole line over the first. Continue in this way until you’ve covered the whole dish. In the same way, lay out a layer of zucchini slices. Scatter the salmon and the chopped dill over the zucchini, then cover with another layer of sweet potatoes, and finish with a layer of zucchini.
Bring the milk back to a simmer, then pour evenly over the pan contents. Pick out the garlic and discard. Cover with foil, and bake for 15 minutes.
Meanwhile, heat the cream and the remaining 2 Tbsp of butter on the stovetop until bubbles appear around the edge of the saucepan. Once the casserole has baked for 15 minutes, remove the foil and pour the hot cream over the pan.
Bake for 25-30 minutes, uncovered, until the bubbling cream around the edges of the pan has begun to clot and brown slightly. Let sit for 10 minutes, then serve in large rectangles.
I first made this without the salmon, and it’s very good that way, too. Simply omit the salmon and the dill. Delicious and vegetarian!
Or, if you’re feeling flush, double the salmon. Right now this is a vegetable dish with a bit of salmon flavor; doubling the fish will make it taste much more like a fish dish.
A smallish amount of grated cheese would also go nicely — I’d suggest a Gruyère, an Emmental, or another of the hard Swiss cheeses. Just a bit will do — no need to overwhelm the rest of the flavors. Sprinkle the cheese over the top of the dish for the second bake, after you’ve poured in the cream.