This Sweet Potato Gratin with rosemary and sage is a festive, elegant side dish. Serve with turkey, sausage cornbread dressing, and loaded green bean casserole for a holiday spread your guests will love.
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This post was originally published in November 2019 and has been updated.
I have a weakness for comforting side dishes like this roasted cauliflower gratin, these make-ahead mashed potatoes with cream cheese, and this hashbrown potato deluxe casserole.
This sweet potato au gratin is an easy, comforting side dish perfect for any holiday table or seasonal gathering. Sliced Russet and sweet potatoes are layered and baked in an herb-infused sauce that smells as wonderful as it tastes.
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Why This Recipe Works
- Sweet potatoes and fresh herbs amp up this dish with glorious seasonal flavor.
- Potatoes baked in a creamy sauce are ultra comfort food.
- The elegant - yet easy - presentation makes it a show-stopping addition to any holiday meal.
Ingredient Notes
- Sweet potatoes add a wonderful sweetness and seasonal flair to this gratin.
- Russet potatoes are the perfect choice for this dish. They are starchy and will soften beautifully as the gratin bakes.
- Sage and rosemary - There's no match for fresh herbs in this dish. Their aroma is as wonderful as their flavor. They add delicious warmth that pairs so beautifully with the creamy potatoes. Fresh thyme leaves can also be used.
- Parmesan cheese adds another layer of flavor with its sharp bite. Nutty Gruyere is also a delicious option.
- Heavy cream creates a rich, thick sauce. Half-and-half can also be used, but I don't recommend using milk. It won't create the same rich result.
See the recipe card for complete instructions and ingredient amounts.
How to Make Sweet Potato Gratin
Step 1: Slowly warm the heavy cream and herbs in a small saucepan over low heat. Meanwhile, using a mandoline, slice the peeled potatoes into thin slices, ⅛-inch think. Layer the potatoes in a greased casserole dish, alternating the Russet and sweet potato slices.
Step 2: Strain the warm cream mixture over the potatoes. If necessary, add more cream - enough so that the cream comes up the sides of the potatoes. (The cream shouldn't completely cover the potatoes).
Step 3: Cover and bake for 35-45 minutes or until fork-tender.
Step 4: Top with Parmesan cheese and bake, uncovered, for another 5 minutes until the cheese is melted and the top is lightly browned.
Expert Tips
- Cut the potatoes into thin slices. Uniformly sliced potatoes will ensure even cooking. A mandoline is a useful tool for making easy work of slicing potatoes in thin slices. If you don't have a mandoline, a sharp knife can also be used. Thin-sliced potatoes will cook faster than thicker ones.
- Infuse the cream with fresh herbs. Fresh rosemary and sage take these potatoes over the top. Don't skip this step!
- Layer the potatoes for a pretty presentation. The presentation gives this dish a special touch - and it's SO easy. Use a round, shallow baking dish to achieve a circular presentation. Alternate slices of russet and sweet potato, fanning them out slightly. The colors are so pretty when presented this way.
Sweet Potato Gratin FAQs
Sweet potato gratin pairs beautifully with holiday turkey or ham, but it's also delicious for Sunday dinner or any seasonal meal.
Store leftovers covered in the refrigerator for up to 3 days. Reheat small portions in the microwave or reheat the casserole dish covered with aluminum foil in a 350℉ oven.
A gratin is a dish with a browned crust on top, often achieved by topping the dish with cheese. Dauphinoise is a dish of thin-sliced potatoes cooked in cream and traditionally does not contain cheese.
Yes, this sweet potato gratin is a great make-ahead dish. Cook, then cool completely. Cover and refrigerate. To reheat, do so covered in a 350℉ oven.
Try These Potato Recipes Next
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📖 Recipe Card
Sweet Potato Gratin
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EQUIPMENT
Ingredients
- 2 cups heavy cream (plus more as needed)
- 2 sprigs rosemary
- 1 bunch sage (8-10 leaves)
- ½ teaspoon Kosher salt
- ½ teaspoon black pepper
- 2 large russet potatoes
- 2 large sweet potatoes
- ⅓ cup grated Parmesan cheese
Instructions
- Preheat the oven to 400℉.
- Add the heavy cream, rosemary, sage, salt and pepper to a small saucepan. Warm the cream slowly over low heat.2 cups heavy cream, 2 sprigs rosemary, 1 bunch sage, ½ teaspoon Kosher salt, ½ teaspoon black pepper
- Meanwhile, peel the potatoes and slice them into thin slices approx ⅛-inch thick. A mandoline works well for this but a sharp knife can also be used.2 large russet potatoes, 2 large sweet potatoes
- Layer the potatoes, alternating slices of russet and sweet potato, in a circular fashion in a shallow casserole dish.
- Strain the cream mixture over the potatoes. If necessary, add more cream - enough so that the cream comes up the sides of the potatoes. (The cream shouldn't completely cover the potatoes).
- Cover and bake for 35-45 minutes or until tender. Uncover and top with Parmesan cheese. Bake uncovered for another 5 minutes until cheese is melted and slightly brown. Garnish with fresh rosemary and sage leaves before serving.⅓ cup grated Parmesan cheese
Notes
- Uniformly sliced potatoes will ensure even cooking. A mandoline is a useful tool for making easy work of slicing potatoes in thin slices. Thinner sliced potatoes will cook faster than thicker ones.
- Infuse the cream with fresh herbs. I love fresh rosemary and sage, and infusing the cream with these flavors takes these potatoes over the top. Don't skip this step!
- To make ahead, cook and cool completely. Cover and refrigerate. To reheat, do so covered, in a 350°F oven.
- Store leftovers in the fridge for up to 3 days.
Nutrition
Nutritional information is an estimate and will vary depending on the exact amounts and specific ingredients used.
Abbey McDermott says
The seasonal flavors in this gratin are a favorite of mine. This casserole is the perfect addition to any fall meal.