Sweet Potato Gratin

Sunday, November 15, 2009

As featured in Bay Area Bites, October 14, 2009.

Sweet Potato Gratin

Sweet Potato Gratin

Turkey season is upon us, and for me, that means sweet potato season! I love sweet potato in pretty much any form — baked, fried, pie’d — but in this gratin form, it is savory-sweet bliss at its finest.

I first discovered this recipe years ago at a potluck in Brooklyn (thanks, Heidi, for sharing). I’ve since made it every Thanksgiving. It is the perfect sweet potato side dish for your table. Yes, this means your aunt can stop bringing those awful candied yams with marshmallows on top. Ickk.

The prep is the most tedious part of this dish, but it can be made a breeze if you have a good mandolin or food processor with a slicing attachment. If you are going the old fashioned knife route, I find it easier to nuke the potato just a minute or so to soften it before attempting to cut into thin slices. Don’t worry if your slices are not perfect, they will be covered with delicious crunchy topping anyway.

Sweet potato prep

Sweet potato prep

Back to the savory-sweet bliss part. If you’re always walking the line between salty and sweet, meet in the middle au gratin, and come with a big serving spoon. The earthy sweetness of the potato anchors this dish, while savory sweet onions add an aromatic dimension. The thyme complements the sweet potato well without overpowering it with herby-ness. Heavy cream and butter make this a holiday dish (don’t skimp, it’s worth it). And, the topping, mmm…extra crunchiness from the panko offsets the soft texture of the gratin, Parmigiano brings even more buttery, savory, goodness into the picture, and pecans top it all off with toasted nuttiness, tinged with a sweet maple flavor.

Make this dish ahead of time to save on holiday stress. Simply prepare it up to the topping part. That way, come meal time, all you have to do is sprinkle the topping, drizzle with olive oil, and pop it in the oven until heated through and golden on top.

Leaves you more time to figure out what to do with Aunt Ro’s marshmallows.


Sweet Potato Gratin

The perfect combo of savory/sweet, this Sweet Potato Gratin is one of my all-time faves.

Prep Time: 30 minutes

Cook Time: 50 minutes

Total Time: 1 hour, 20 minutes

Yield: 10-12 servings


4 pounds sweet potato
2 pounds onions
4 tablespoons unsalted butter
2 cups heavy cream
2 tablespoons fresh thyme, roughly chopped
1 teaspoon salt
1 teaspoon black pepper
¼ teaspoon cayenne pepper
1 cup panko bread crumbs
1 cup pecans, chopped
¼ cup grated Parmigiano
Olive oil for drizzling


  1. Heat the oven to 350°F and arrange a rack in the middle. Butter a 13-by-9-inch baking dish and set aside.
  2. Thinly slice the onions. Melt butter in a medium frying pan over medium-low heat. When it foams, add onion and season well with salt and pepper. Slowly cook until soft and translucent (about 20 minutes); set aside.
  3. Peel sweet potatoes and cut into 1/8-inch slices with a mandolin, sharp knife, or food processor with slicer attachment.
  4. Mix the cream, cayenne and thyme leaves in a large bowl and set aside.
  5. In the baking dish, layer 1/3 potato slices on the bottom, 1/3 cream mixture, a liberal sprinkle of salt and pepper, and 1/2 of the onions. Repeat, layering another 1/3 of potato slices, 1/3 cream mixture, salt and pepper, and the rest of the onions. Finish off with the last of the sweet potato and cream mixture, and a sprinkle of salt and pepper.
  6. Cover with foil and bake 40-50 minutes (it should be soft and cooked through).
  7. Combine panko, pecans, and Parmigiano. Sprinkle mixture evenly over gratin. Drizzle with a little olive oil to help with the browning. Bake uncovered, about 10 minutes, until golden. Keep an eye out to make sure the pecans do not burn. (Make ahead note: You can make the day before serving, baking without the topping. Bring to room temperature, cover and refrigerate. The next day, add the crunchy topping mixture and bake until golden and warmed through.)

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Posted by Stephanie at 2:00 pm

11 Responses to “Sweet Potato Gratin”

  1. Now this looks good, my SIL loves sweet potatoes with marshmallows on top which is too sweet for me – this on the other hand I could eat a lot of leftovers of, if I managed to hid some in back of the fridge.

  2. I love sweet potatoes and always on the look out for new recipes. Will be trying this one. Love this it is on the savory side vs. sweet side.

  3. This sweet potato gratin looks gorgeous! I’m glad to see a recipe that balances the sweet and salty with sweet potato.

  4. Rose says:

    Looks great! I love sweet potatoes!! I’m not a big fan of marshmallows so I generally leave them off my food too ;)

  5. This is a good recipe for thanksgiving,you give me an idea on a new sweet potato recipe. Sweet potatoes are nice and sweet but your recipe balances all flavors of the rest of the ingredients so it is indeed a great menu on any occasion.

  6. Marvelous! I love sweet potato in nearly all its forms, especially pies and fries. This gratin is a great alternative to the strange marshmallow-topped version (although I do enjoy ones that have a crumble topping!)

  7. [...] the addition of jalapeno and lime gives a swift ninja kick to the traditional cranberry sauce.3. Sweet Potato GratinSweet Potato GratinThis dish has become a classic addition to my Thanksgiving table. It’s a [...]

  8. Sally says:

    I want to prep this for Thanksgiving! Are the pecans plain, or toasted?

    • Stephanie says:

      Hi Sally,
      No need to toast the pecans before topping the sweet potatoes b/c they’ll be going in the oven! Enjoy this, it’s one of my faves, and ALWAYS a hit at Thanksgiving :)

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