Rosemary Sweet Potato Gratin (Vegan + Gluten-Free)

This Sweet Potato Gratin is spiced with rosemary, thyme, and nutmeg, and coated in a dairy-free cheesy sauce for a hearty and cozy dinner side. 

I just found my new favorite way to enjoy sweet potatoes – this Sweet Potato Gratin! What’s not to love about tender sweet potatoes layered in a creamy “parmesan” sauce and herb sauce, then baked until crisp and bubbly? I’ll tell ya – not much.

Plus, this allergen-friendly version is dairy, nut, and gluten-free! It’s basically the perfect side dish, and can be served with a simple weeknight dinner or holiday feast.

INGREDIENTS + INSPIRATION

Gratin is derived from the French au gratin, which means “by grating” or “with a crust.” It’s a type of casserole dish made of thinly sliced vegetables topped with a crispy coating – usually melted cheese or breadcrumbs. A gratin is typically known for its crust, while scalloped potatoes are usually cut thicker; they’re still served with a cream sauce, but don’t have a crispy coating.

Technically speaking, this recipe would be more like scalloped sweet potatoes/gratin fusion. Thinly sliced sweet potatoes get tossed and layered in a creamy dairy-free parmesan cheese sauce, mixed with fresh thyme and rosemary, and then baked until bubbly.

HOW TO MAKE SWEET POTATO GRATIN

Like all gratins, this plant-based version is baked in the oven for those deliciously crispy sweet potato edges and a bubbly (dairy-free) cheese sauce. The main difference in this recipe vs. others is that I prefer to pre-mix the sweet potatoes with the sauce before placing them in the casserole dish, rather than only pouring the cream sauce on top. I find this gives the dish more of an even flavor distribution as well as layer separation in the gratin.

1. Peel the sweet potatoes, thinly slice with a mandoline, then set aside.
2. Prepare the cheese sauce by blending grated parmesan, garlic, nutritional yeast, non-dairy milk, arrowroot powder, and spices
3. Mix in a large bowl with the sweet potatoes and fresh herbs, then layer into a baking dish
4. Bake until golden and bubbly, then serve warm.

The upper edges of this sweet potato gratin get nice and crisp, but if you’d like more of a traditional crust you can also sprinkle up to 1 cup of dairy-free cheese over the gratin before baking. Either way, don’t skimp on the black pepper – I love the smoky kick of flavor it adds to this recipe!

You can serve this Sweet Potato Gratin as a tasty weeknight dinner side, but it also is fancy enough to enjoy over a lovely holiday dinner, too. I like to think of it as a savory alternative to the classic sweet potato casserole 🙂

FAQ + TROUBLESHOOTING

• Kitchen Tools: I highly recommend using a mandoline to slice your sweet potatoes as thinly as possible – this will ensure your sweet potatoes get tender, and will give better textural results. You can also use a sharp knife to slice your potatoes, but unless you are a pro, it will be hard to get them as thin as you want
• Prevent Burning: if you find that your gratin is cooking too quickly on the top and starting to burn, cover it with aluminum foil for the remainder of the bake time
• Make it Cheesy: Top your gratin with up to 1 cup of dairy-free cheese for an extra crisp and delicious dish
• Other Flavor Variations: feel free to add in more of your favorite herbs, like sage or even oregano!

If you’re looking for more sweet potato recipes, check out this Sweet Potato Lentil Soup, these BBQ Sweet Potato Tofu Tacos, and for something sweet, these Stovetop Candied Sweet Potatoes with Pecans! 

Finally, if you make this recipe and decide to share it on Facebook or Instagram, don’t forget to tag me @FromMyBowl + #FromMyBowl! I love seeing your delicious recreations 🙂

Vegan Sweet Potato Gratin

Print Recipe

★★★★★

5 from 6 reviews

This Sweet Potato Gratin is spiced with rosemary, thyme, and nutmeg, and coated in a dairy-free cheesy sauce for a hearty and cozy dinner side. 

• Author: Caitlin Shoemaker
• Prep Time: 10 Minutes
• Cook Time: 55 Minutes
• Total Time: 1 hour 5 minutes
• Yield: Serves 4 to 6 1x
• Category: Side
• Method: Oven
• Cuisine: American
• Diet: Vegan

Ingredients

Scale 1x2x3x

• 2 pounds (910 g) sweet potatoes (about 2 medium sweet potatoes)
• 2 tablespoons nutritional yeast
• 2 tablespoons arrowroot powder or cornstarch
• 2 ounces (57 g) dairy-free parmesan cheese*, grated
• 1 tablespoon olive oil
• 3–5 cloves garlic
• 1/2 teaspoon ground nutmeg
• 1/2 teaspoon black pepper, or to taste
• 1 teaspoon salt
• 1 3/4 cups (415 ml) full-fat oat milk*
• 3 sprigs of thyme, leaves de-stemmed
• 1 teaspoon finely chopped rosemary

Instructions

1. Prep: Preheat the oven to 400F and lightly grease a a 9″ oval baking or gratin dish (or similar sized) with nonstick cooking spray. Set aside. Peel your sweet potatoes, then use a mandoline to slice them as thin as possible; I sliced mine to about 1/8 inch. Place the sweet potatoes in a large bowl, then set aside.
2. Make the Sauce: Add the nutritional yeast, arrowroot powder, vegan parmesan, oil, garlic, nutmeg, pepper, salt, and milk to a high-speed blender. Blend on high for 45 to 60 seconds, or until a uniform sauce forms. Pour the sauce mixture over the sweet potatoes and add in the thyme and rosemary. Use a spatula (or your hands) to mix well, making sure each piece is evenly coated. Mixing the sweet potatoes ahead of time ensures better flavor and sauce distribution.
3. Arrange & Bake: Use your hands to transfer the sweet potato wedges into your baking dish. For the best gratin texture, it’s best to form “stacks” or columns of potato slices, then to lay them into the dish (see recipe notes or video for more details). Place the gratin in the middle rack of the oven and bake for 55-60 minutes, until the sauce is bubbly, but firm.
4. Serve: Remove the casserole from the oven and let sit for 5 minutes before serving, to allow the sauce to set. Serve warm; leftovers will keep in the refrigerator for up to 5 days, or can also be frozen for up to 2 months.

Notes

• Parmesan: I like to use Violife parmesan cheese for this recipe and grate it myself, but another brand of shredded cheese should work too. If you have a high-powered blender (like a Vitamix) you only need to chop your cheese, not grate it.
• Milk: oat milk can be replaced with lite coconut milk, or a creamy homemade nut or seed milk.

Keywords: scalloped sweet potatoes, healthy scalloped sweet potatoes, vegan scalloped sweet potatoes