This healthier sweet potato gratin is the perfect holiday side dish! It’s dairy-free, paleo, whole30, AIP, and vegan-friendly.

Sweet Potato Gratin

What is Sweet Potato Gratin?

Also referred to as scalloped potatoes, potato gratin is a dish made from thinly sliced potatoes and baked in a creamy cheesy sauce. How could you go wrong?! This dish is perfect for the holidays, and is easier to make than it looks, but seems like you spent hours making a beautiful dish.

As this recipe is traditionally made with white potatoes, heavy cream, and cheese, I’ve decided to make a modified version with sweet potato, coconut milk, and seasonings and herbs to give it that seasonal flavor! This recipe is paleo, whole30, dairy-free, nightshade-free, AIP, and vegan-friendly. It’s perfect for serving at a holiday gathering to share with others of all dietary needs!

How to Make Sweet Potato Gratin

Sweet Potato Gratin

Tips & Tricks for Making Sweet Potato Gratin

Use a mandolin slicer

You don’t need to do this, but it helps make the cuts easier!

Taste the sauce and season as you go

Nutritional yeast is one of those things that can taste a bit differently to everyone, so you’ll want to taste as you go!


Can you make this sweet potato gratin ahead of time?

Sure! It’s best fresh, but you can easily reheat it under the broiler.


Do you need an oval casserole dish for this recipe?

Nope! I think it looks prettiest in an oval dish, but you can also use a square or rectangular casserole dish and layer the sweet potatoes in 3-4 vertical rows.

The Ingredients (and substitutions)

Sweet potato 

It’s best to pick sweet potatoes that are nice and round to make prettier rounds for the casserole.

Coconut milk

Full fat coconut milk (I use canned) is the best dairy-free option for making this recipe dairy-free. Almond milk is a bit thinner, but you can try to use that as a substitute.

Onions, shallots & garlic

These add lots of flavor to the sauce.

Arrowroot starch

Arrowroot helps to thicken the sauce. You can try and use tapioca starch if that’s what you have on hand, but I think arrowroot works best in savory dishes.

Nutritional yeast & sage

Nutritional yeast makes this recipe taste cheesy! You can leave it out, but it won’t taste as much like a traditional au gratin.

Sweet Potato Gratin

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Healthy Sweet Potato Gratin (Whole30, Vegan)

  • Author: Michelle
  • Total Time: 55 minutes
  • Yield: 6 servings 1x


This healthier sweet potato gratin is the perfect holiday side dish! It’s dairy-free, paleo, whole30, AIP, and vegan-friendly.


  • 23 tbsp coconut oil, divided
  • 3 large sweet potatoes
  • 1 1/2 full fat cup coconut milk
  • 2 tsp arrowroot starch
  • 24 tsp nutritional yeast (adjust to taste)
  • 1 tsp dried sage
  • 1/2 tsp dried thyme
  • 1 tsp sea salt
  • 1/4 tsp black pepper (omit for AIP)
  • 1 yellow onion, diced
  • 2 cloves garlic, minced
  • 1/2 small shallot, thinly sliced


  1. Preheat the oven to 400 F and prepare a large, oval casserole dish (I used a 9×13″) by greasing with coconut oil.
  2. Scrub the sweet potatoes well and slice into thin rounds (about 1/8″-1/4″ thick) either using a sharp knife, or a mandolin slicer. Arrange the sweet potatoes in a circular formation on the edge of the casserole dish, overlapping them as you go. Layer the remainder of the sweet potatoes in the center of the circle, in a straight line. Alternatively, you can layer the sweet potato slices in vertical rows if you’re using a square or rectangular casserole dish. Set aside.
  3. In a separate bowl, whisk together the coconut milk, arrowroot starch, nutritional yeast, sage, salt and pepper. Whisk well to throughly combine and set aside.
  4. Using a medium stock pot, heat 1 tbsp of coconut oil on medium heat. Add the onion, shallots and garlic and cook for 3-4 minutes or until the onion is transluscent.
  5. Pour the coconut milk mixture over the onion mixture and whisk well to combine. Simmer for 3-4 minutes to allow the mixture to thicken. Remove from heat.
  6. Begin slowly pouring the coconut milk mixture over the sweet potatoes. Use a rubber spatula to spread the liquid between the sweet potatoes slices and evenly coat over the top until all of the mixture is used.
  7. Bake in to the preheated oven for 35-40 minutes or until the sweet potatoes and cooked and the sauce has lightly browned.
  8. Serve fresh with a serving spoon.


All nutritional information are estimations and will vary. Estimations do not include optional ingredients.

  • Prep Time: 20
  • Cook Time: 35
  • Category: Sides
  • Method: Baked


  • Serving Size: 1 serving
  • Calories: 205
  • Fat: 14.4g
  • Carbohydrates: 18.5g
  • Fiber: 2.6g
  • Protein: 2.7g

Sweet Potato Gratin