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The Best Low-Carb "Potato" Gratin

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Potato Gratin, also known as Potato Dauphinoise is one of the meals I didn't want to give up when I started following a low-carb diet. When looking for a keto alternative, I spent quite some time trying to figure out what works best instead of potatoes.

Cauliflower was the first substitute I tried but wasn't happy with the result. There is a better ingredient for making low-carb potato gratin - rutabaga, also known as swede. Although rutabaga contains more carbs than cauliflower, in my opinion it's worth using it in this recipe.

I've been using this amazing low-carb vegetable for years - mostly in soups and stews like this one. It has proven to work even for keto fries and makes the best potato salad - a traditional Czech Christmas side dish that is served with breadcrumbed fried fish.

You could try other vegetables too - kohlrabi or turnips are also good options. Just for a comparison (per 100 grams/ 3.5 ounces):

  • white potatoes - 13.3 g net carbs (15.7 g total carbs)
  • sweet potatoes - 17.2 g net carbs (20.3 g total carbs)
  • turnips - 4.6 g net carbs (6.4 g total carbs)
  • rutabaga / swede - 6.3 g net carbs (8.6 g total carbs)
  • cauliflower - 3 g net carbs (5 g total carbs)
  • kohlrabi - 2.6 g net carbs (6.2 g total carbs)
  • celery root - 7 g net carbs (9 g total carbs)
  • radishes - 1.8 g net carbs (3.4 g total carbs)
  • daikon radish - 4 g net carbs (6 g total carbs)
  • parsley roots - 1.7 g net carbs (3.5 g total carbs)

Since it's the Holiday season, make sure you check out my festive keto recipes!

Hands-on Overall

Serving size about 200 g/ 7 oz

Allergy information for The Best Low-Carb "Potato" Gratin

✔  Gluten free
✔  Egg free
✔  Nut free
✔  Nightshade free
✔  Avocado free
✔  Coconut free
✔  Fish free
✔  Shellfish free
✔  Beef free

Nutritional values (per serving, about 200 g/ 7 oz)

Net carbs10.4 grams
Protein13.6 grams
Fat37.7 grams
Calories445 kcal
Calories from carbs 10%, protein 13%, fat 77%
Total carbs13.5 gramsFiber3.1 gramsSugars7.1 gramsSaturated fat21.1 gramsSodium752 mg(33% RDA)Magnesium44 mg(11% RDA)Potassium619 mg(31% EMR)

Ingredients (makes 8 servings)

Baked "potatoes":
  • 1 kg rutabaga, about 2 large pieces (2.2 lb)
  • 3 tbsp ghee or lard (45 g/ 1.6 oz)
  • 1 small white onion (70 g/ 2.5 oz)
  • 8 large slices bacon (240 g/ 8.5 oz)
  • 1-2 tbsp freshly chopped thyme or 1-2 tsp dried thyme
  • 1 cup heavy whipping ream (240 ml / 8 fl oz)
  • 3 cups chicken stock, vegetable stock or bone broth (720 ml/ 24 fl oz)
  • 1 cup grated cheddar cheese (110 g/ 4 oz)
  • 1 tsp sea salt or more to taste
  • freshly ground black pepper
  • 1/2 cup creme fraiche or sour cream (120 g/ 4.2 oz)
  • 1/2 cup grated Parmesan cheese (45 g/ 1.6 oz)


  1. (Note: This recipe is best prepared a day in advance as it will have time to soak up any excess juices.) Preheat the oven to 160 °C/ 320 °F (fan assisted), or 180 °C/ 355 °F (conventional). Peel and slice the onion and place in a hot pan greased with ghee. Cook over a medium heat until fragrant for about 5 minutes while stirring. The Best Low-Carb "Potato" Gratin
  2. Slice the bacon and add to the pan with the onion. Add thyme and cook until the bacon is lightly browned from all sides. Take off the heat and set aside. The Best Low-Carb "Potato" Gratin
  3. Meanwhile, peel and halve the rutabaga. Cut thinly, into about 1/4 cm (1/8 inch) slices. (Note: If you want to reduce the baking time to just 45-50 minutes, pre-cook the rutabaga. Place in a pot filled with water and cook for about 10 minutes. Then, drain and use as described in the following steps but with only 1 cup of the stock instead of 3 cups. Remove the baking foil and top with creme fraiche and Parmesan cheese for the last 20 minutes of the cooking process.) The Best Low-Carb "Potato" Gratin
  4. There will be three layers of rutabaga. Place the first layer of slices into a large baking dish greased with some ghee. Top with half of the bacon and onion mixture. The Best Low-Carb "Potato" Gratin
  5. Add half of the grated cheddar cheese. Top with another layer of rutabaga slices, bacon, onion and grated cheddar. Finally, top with the last layer of rutabaga slices. In a bowl, combine the cream, chicken stock, salt and pepper. The Best Low-Carb "Potato" Gratin
  6. Pour into the baking dish over the rutabaga until almost covered. If needed, add some more chicken stock. Season with more salt and pepper to taste. The Best Low-Carb "Potato" Gratin
  7. You can use one large baking dish or a single-serving baking dish like this one from Le Creuset. The Best Low-Carb "Potato" Gratin
  8. Cover with aluminum foil and transfer into the oven over a baking dish to collect any juices dripping from the aluminum cover. Bake covered for an hour.
  9. After an hour, the rutabaga will get softer. Remove the aluminum foil and press the rutabaga down with a spatula to submerge it into the cream mixture and prevent it from drying. Bake for another 45-60 minutes or until the rutabaga gets tender, pressing it down with a spatula every 15 minutes. When done, remove from the oven and set aside. Turn the oven up to 200 °C/ 400 °F (fan assisted), or 220 °C/ 425 °F (conventional). The Best Low-Carb "Potato" Gratin
  10. Spread the creme fraiche and grated parmesan cheese on top. The Best Low-Carb "Potato" Gratin
  11. Place back in the oven for another 20-30 minutes or until the cheese is melted and the top is crispy and golden brown.
    I baked mine a day ahead, let it chill and stored in the fridge to set. Then I made the final browning just before serving. This way if wasn't burning hot, was perfectly set and ready to be served straight from the oven. The Best Low-Carb "Potato" Gratin
  12. Serve as a side with meat or fish, or as a light lunch - by itself with some crispy greens. It tastes great both hot and cold. The Best Low-Carb "Potato" Gratin
  13. Store in the fridge for up to 5 days. Enjoy! The Best Low-Carb "Potato" Gratin

Ingredient nutritional breakdown (per serving, about 200 g/ 7 oz)

Net carbsProteinFatCalories
Swede (rutabaga), fresh
7.9 g1.4 g0.2 g46 kcal
Onion, white, fresh
0.7 g0.1 g0 g4 kcal
Cream, heavy whipping, pouring, full-fat (30-40% fat)
0.8 g0.6 g11.4 g110 kcal
Chicken stock (broth), chicken only, homemade
0 g1.8 g1.8 g23 kcal
Crème fraîche
0.5 g0.5 g5 g47 kcal
Parmesan cheese
0.2 g2 g1.5 g22 kcal
Thyme, fresh
0 g0 g0 g0 kcal
0 g0 g5.6 g51 kcal
Salt, pink Himalayan rock salt
0 g0 g0 g0 kcal
Pepper, black, spices
0 g0 g0 g0 kcal
Cheddar cheese
0.4 g3.2 g4.7 g57 kcal
Bacon, streaky (high fat content), organic
0 g4.1 g7.5 g84 kcal
Total per serving, about 200 g/ 7 oz
10.4 g13.6 g37.7 g445 kcal

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Martina Slajerova
Creator of

Martina Slajerova

I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight.

That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food.

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Comments (22)

This has great flavor, but I too had the soupy issue. It wasn’t until I was partway through cooking it, that I read you make this a day ahead of time. I’ll admit that I should’ve read the recipe through before starting it, but I was in a rush and just wanted to get dinner going. I did read your intro before starting, though, so I think it would be a good idea to let people know there to prep 1 day in advance.
I followed your tip of precooking the rutabaga in boiling water, so I’m wondering if the dish still really needs 4 cups of liquids (chicken stock & cream)? Isn’t most of that liquid to thoroughly cook the rutabaga? Also, there are no modified oven steps for the pre-cooked 45 minute method. When do I take the foil off? At the 20min mark? 15-min intervals of pushing the rutabaga into the liquid doesn’t make sense for a 45-min total bake.
Like I said, the flavours are spot on, even if I did have to eat it out of a bowl, so I plan to try this again, but I’ll probably halve the chicken stock, if not more. Regular potato gratin can be cooked in the same evening it’s prepped, so I’m sure with some tweaks, this one can be too.

You are right, I should mention the fact it is best prepared a day in advance at the beginning of the preparation.
If you used the pre-cooking method, I'm sorry this wasn't clear, I realised that with reduced cooking time I should have mentioned to reduce the liquid needed. I included this tip but it was incomplete - I added that now.
Thank you so much! I haven't revisited this recipe for a while now so it's good you noticed. I hope the next batch comes out great!

I tried this again with your modified directions for pre-cooked rutabaga, and it was perfection. I didn't even need to cook it the day before. After removing the foil after 20mins, I cooked it uncovered for 25mins more, then added the sour cream & parm, and baked it for 15mins, then broiled for the last 5mins.
This was such a huge success at my table!

Thank you so much, I'm so happy to hear that this was a success!

Sorry but this was very soupy. Not a repeat at this table.

I'm sorry to hear that, perhaps there was more moisture in the rutabagas. It really helps to refrigerate this overnight. All of the moisture in mine was gone in the morning 😊

I made this dish last night and it was delicious! Very rich and indulgent. From the other comments, I was concerned that it might be too liquid, so after I sliced the Swede, I salted the slices and let them sweat out some of their moisture prior to cooking. However, at the end of the cooking time it was looking a little soupy, so I left it in another 15 minutes and then took it out to rest for about 15 minutes and it solidified nicely. I cut it in large slices, which held together well. Another great dish, thank you Martina!

Thank you for your kind words and great tips!

Thank you so much for this recipe. I cooked it tonight and my husband loved it. I personally eat low carb for years , but my husband who has Diabetes 2 did not really go for it. I have your books too and I really enjoy to try new ideas , it is fun and I slowly will give my husband more keto food.

Thank you so much for your lovely feedback!

I also had the soupy issue... made these yesterday while we were all home for a snow day.  The taste was amazing.  Even the next day after being refrigerated all night, there's no way that would stand up to being held up on a spatula like your photo... You didn't add any kind of thickening agent?  no corn starch or coconut flour or anything of the sort?

Hi Stephanie, no I didn't. There was a slight moisture issue (see the last photo) when it was freshly baked but it was gone the day after. I suppose this could be due to different evaporation, or maybe fat content of the cream (I used heavy whipping, slightly below 40% fat).

Just made this today and for some reason it never solidified while baking it. It's like soup. Any suggestions? I double checked and I believe I followed the directions closely and measured the right amount of cream/chicken broth, etc. Thoughts?

That's interesting. I double checked the amounts and they should all be correct. When it's freshly baked, there are more liquids and it solidifies as it cools down. The last image was taken right after baking and the one before was taken the day after (no liquids).

I made this with turnips (I bought them by accident because they LOOK THE SAME!I knew as soon as I started peeling they were turnips) anyway,  it was good.  Paired really well with salmon.

Turnips are great and contain less carbs so it was a good swap 😉

Have you any experience with jicama? I remember eating it as a raw vegetable years ago---it's crunchy when raw, without much flavor, not sweet, somewhat similar to white potato. It's also very low glycemic load, so I thought it might be useful in stews, gratins and so on.

That may work too! I wish I could get it where I live. We don't seem to have jicama in the UK...

What do you think about using celery root in this recipe?

Good point, I've added celeriac to the list, yes it will work too 😊

It seems the kind of comfort food perfect for a cold winter! If only I could find rutabaga here! What about topinambour? You did not mention it, though it works finely in potatoes' recipes.
Thank you

It is! Jerusalem artichoke (topinambour) has more carbs than white potatoes - it's closer to sweet potatoes. So if you don't mind that I think it will work 😊