Sweet Potato Parmesan Gratin

I write this post on a full belly, the best kind of belly if you ask me. I dined on leftover pancakes and a chocolate breakfast shake and it’s approximately 11:45 a.m. The fact is, when you work at home some days you don’t wake up until 8:30 and you don’t shower until 10, which means you don’t have coffee ’til 11 and simply are not hungry for breakfast until noon. But if you ask me, what’s the big deal? My belly got fed either way…

Speaking of full bellies, this sweet potato gratin gave me a full belly. Sliced sweet potatoes with one wee little yellow potato in the mix, sprinkled with a touch of thyme, lots of fresh grated Parmesan cheese and baked to perfection – this is the breakfast, brunch, lunch, snack of champions.

I love how simple this dish is to throw together. It’s rustic in nature: loosely sliced sweet potatoes, a touch of salt, pepper and thyme, fresh grated cheese and a splash of milk. Throw her in the oven for an hour or so and you have a stunning and tasty dish on your hands. I personally prefer mine as an addition to lunch, but it also would be perfect alongside eggs or fruit for breakfast or as an afternoon snack.

The best part? It’s good hot, warm and room temperature meaning it’s a no-fuss kind of meal. If you haven’t guessed by now, that’s my kind of meal.

4.3 from 3 reviews
Sweet Potato Parmesan Gratin
Prep time
Cook time
Total time
A simple gratin featuring sweet potatoes, thyme, low-fat milk and parmesan cheese. Healthier than your average gratin yet just as satisfying.
Recipe type: Side Dish
Serves: 5-6
  • 2 organic sweet potatoes, sliced in thin rounds
  • 1 small red or yellow potato
  • ~ 1/4 tsp each salt and freshly ground pepper
  • 1 tsp thyme, roughly chopped (fresh or dried)
  • 3/4-1 cup Parmesan cheese, finely grated
  • 2 cups low-fat milk (I used 2%)
  1. Preheat the oven to 400 degrees.
  2. Butter or lightly oil a baking dish or cast iron skillet.
  3. Place the sliced potatoes in a bowl and season generously with salt and pepper. Add the thyme and half of the cheese and toss together.
  4. Transfer to the dish and pour on the milk. It should just cover the potatoes.
  5. Bake 30 minutes, remove from oven and carefully drain off a bit of the liquid (about 1/3 cup). Sprinkle the remaining cheese over the top and return to the oven.
  6. Bake another 45-50 minutes, until the milk is absorbed, the potatoes are soft and the top and edges are golden and around the edges. (Optional: drain off a bit more of the liquid as using low-fat milk instead cream can result in a bit of wateriness.)
  7. Let rest at least 20 minutes before serving so the juices can redistribute.
  8. Can be made ahead of time and reheated in the microwave or oven for serving.
* You can use cream or half and half instead of low-fat milk, but it will add a lot more fat and calories overall.
* You can substitute other cheeses besides parmesan, such as gouda or asiago.
Nutrition Information
Serving size: ~5 servings; per serving Calories: 200 Fat: 5 g Saturated fat: 3 g Carbohydrates: 27 g Sugar: 6 g Fiber: 3 g Protein: 11 g

danaHi, I'm Dana! I am a food stylist, photographer, and author of the Food Photography School and the 31 Meals Cookbook.

Find me on Twitter, Instagram, and Pinterest.

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Talk About It

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  1. De says

    YUM! I’ve realized I’m obsessed with sweet potatoes so this is perfect for me. I love to use my cast iron skillet too :) Thank you!

  2. Janani says

    So I’m making this tomorrow for Thanksgiving dinner! I wonder how Gruyere cheese will taste with this dish… hmm.. But, for the sake of pleasing everyone- I shall stick to parmesan and asiago!

  3. Sam says

    Is there a functional reason for using a single white potato in the mix? I was wondering if the recipe would still work with all sweet potatoes?

  4. Amy says

    Brilliant recipe! So yummy, I’m sitting here typing this with a full belly thanks to this recipe. Excited to try more of your recipes!

  5. Laura says

    What’s your trick for slicing them so thin? I have the hardest time slicing sweet potatoes into chunks for mashed, I can’t imagine getting them that thin. Did you use a vegetable slicer? Have you ever tried to use one with the sweet potatoes?

    • Dana says

      Nope! I just use a really sharp knife and slice them uniformly thin. Practice makes perfect! Otherwise, get a mandolin – I hear they slice really well.

      • SkippyMom says

        I do exactly the same. I always sharpen my good knife on the bottom of a ceramic coffee mug [try it, it works SO well] as a sharp knife is incredibly important. Uniform size is the key, not so much as the thickness because you want them to cook at the same rate.

        But as you said = practice makes perfect. :) Love the recipe and I have two sweet potatoes and leftover ham just asking to be made into a new dinner. Thanks so much.

  6. Bogna says

    Love it! Simplicity is the best! My friends really enjoyed it! (I’ve got very good feedback!) Question: Could you recommend a good substitute for milk? I’m vegan and try to figure out what the substitute would work for vegan version of this awesome gratin.

  7. Mirandamom says

    Substituted fresh sage for the thyme. The dish was very good but the herbs got lost. If I do it again with sage I’ll double the amount. But I’m thinking next time, rosemary!

  8. Jason says

    Very nice. I had one orange sweet potato and one purple sweet potato on hand. Between the milk and the purple sweet potato, the result looked like pepto bismol surprise but tasted good.

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