A sweet potato gratin recipe with mushrooms is an easy indulgence

Sweet Potato and Mushroom Gratin

active time:20 mins

total time:50 mins


active time:20 mins

total time:50 mins



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After a glorious, too-brief autumn, it feels like winter in Washington. The trees, bare arms outstretched toward the sky, are mostly free of leaves. Fat, furry squirrels leap from branch to branch, chasing one another’s’ tails in a mad quest for the last few acorns. The sun rises later than I’d like, and sets before I’m done writing for the day. Thanksgiving is near, and before long, the end of this year.

I’m slowly getting into holiday mode and looking for excuses to indulge. Sometimes that looks like a caramel-filled bonbon after lunch. Sometimes it might be a crisp gin martini with extra olives. Sometimes it’s a slice of pie in the afternoon. Other days it might be a rich dinner with this sweet potato gratin with mushrooms and thyme at its center.

I started dreaming up this recipe back when the days were still hot and humid. That’s how it is with recipe development — we’re always working a season or two ahead. But I could imagine how chilly the air would get come November, and what I’d want to eat after a damp day of cold, hard rain. Soup is the easy answer, but when you are looking for something a little luxurious, consider this one-pan gratin with tender vegetables bathed in salty, thyme-scented cream, dotted with mushrooms.

A guide to sweet potato varieties: How to choose, prep and store them

I like it served simply, with a quick and crunchy green salad with a lemony dressing on the side to brighten up the plate.

This isn’t everyday food — it’s extravagance. Simple, and not too expensive, the gratin works as a main course or side dish. It might even be nice as a side to your Thanksgiving meal.

Speaking of: That’s the best part of Thanksgiving, isn’t it, the sides? I think so. I can’t wait to load up my plate with stuffing, mashed potatoes, sweet potatoes, green beans, roasted carrots, salad, rolls, cornbread, macaroni and cheese, cranberry sauce and maybe, maybe a tiny bit of turkey.

Sweet Potato and Mushroom Gratin

  • If you can’t have onion >> skip it.
  • No sweet potatoes? >> This would work with thinly sliced ​​squash or other types of potatoes.
  • Out of parmesan? >> Use another hard, meltable cheese such as gruyere or cheddar.

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  • 2 tablespoons unsalted butter
  • 1/4 small yellow onion (1 ounce), sliced ​​(optional)
  • 6 ounces small mushrooms (any kind), sliced
  • 1/4 teaspoon fine salt, plus more as needed
  • 1 3/4 cups heavy cream, divided
  • 3/4 cup (3 ounces) grated parmesan cheese, divided
  • 2 large sweet potatoes (1 1/2 pounds total), peeled and thinly sliced
  • 1 sprig of fresh thyme, plus a few fresh thyme leaves for garnish (optional)

Position a rack in the middle of the oven and preheat to 400 degrees.

In a large skillet over medium-high heat, melt the butter. When it begins to sizzle, add the onion, if using, mushrooms and salt. Cook, stirring occasionally, until the mushrooms release their liquid and begin to brown, about 5 minutes. Add about 1/2 cup of the heavy cream, using it to help you scrape up any browned bits from the bottom of the pan. Add the remaining cream and quickly stir in about half of the cheese. Nestle the sweet potatoes in with the mushrooms, fitting them into a flat layer, and add the sprig of thyme, if using. Bring to a boil. Remove from the heat, cover the skillet tightly with aluminum foil and transfer to the oven.

Roast for 25 minutes, then remove the foil and top with the remaining cheese. Continue roasting, uncovered, for another 10 to 15 minutes, or just until the potatoes are tender. Garnish with thyme leaves, if using, and serve hot, family style.

Calories: 660; Total Fat: 51g; Saturated Fat: 31g; Cholesterol: 177mg; Sodium: 609mg; Carbohydrates: 40g; Dietary Fiber: 6g; Sugar: 9g; Protein: 14g.

This analysis is an estimate based on available ingredients and this preparation. It should not substitute for a dietitian’s or nutritionist’s advice.

From staff writer G. Daniela Galarza.

Tested by Jim Webster; email questions to [email protected].

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Catch up on this week’s Eat Voraciously recipes:

Monday: Spinach and Ricotta Ravioli

Tuesday: Baked Chicken Drumsticks With Spicy Peanut Sauce

Wednesday: Roast Broccoli Hero

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