If you're looking for a scrumptious seasonal side dish, try this Sweet Potato Gratin with Rosemary and Sage. The elegant presentation is second only to the incredible flavor.

Crowd-pleasing dish
This easy yet elegant side dish is perfect for any holiday table or seasonal gathering. This gratin is baked with an herb-infused sauce that smells as wonderful as it tastes.
Why you'll love this gratin
Be sure to try my Roasted Cauliflower Gratin, Best Make-Ahead Fluffy Mashed Potatoes, and Hashbrown Potatoes Deluxe.
Ingredients
- Sweet potatoes add a wonderful sweetness and seasonal flair to this gratin.
- Russet potatoes are 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.
Step-by-step instructions
See the recipe card for complete instructions and ingredient amounts.
- Preheat the oven to 400 degrees.
- Add the cream to a small saucepan. Add the herbs and salt and pepper. Warm slowly over low heat to infuse the cream with the flavor of the herbs.
- Meanwhile, peel the potatoes. Using a mandolin or sharp knife, slice the potatoes into thin slices, approx. ⅛-inch thick.
- Layer the potatoes in a greased casserole dish, alternating the russet and sweet potato slices.
- Strain the warm cream 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 fork-tender. Top with Parmesan cheese and bake, uncovered, for another 5 minutes until the cheese is melted and the top is lightly browned.
Tips for preparing
- Cut the potatoes into thin slices. Uniformly sliced potatoes will ensure even cooking. A mandolin is a useful tool for making easy work of slicing potatoes in thin slices. If you don't have a mandolin, a sharp knife can also be used. Thinner sliced potatoes will cook faster than thicker ones.
- Infuse the cream with fresh herbs. I absolutely love fresh rosemary and sage and infusing the cream with these flavors 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. Use a round shallow baking dish to achieve the circular presentation. Alternate slices of russet and sweet potato, fanning them out slightly. The colors are so pretty when presented this way.
Serving
Sweet potato gratin pairs beautifully with turkey but is also delicious with beef, pork, or ham. As festive as this dish is, you don't have to save this for special occasions. Serve this gratin for Sunday dinner or any fall or winter meal.
Faq's
Gratin is a culinary technique referring to an ingredient topped with a browned crust, usually formed by topping with breadcrumbs, grated cheese, or butter.
As noted above, gratin refers to a dish with a browed 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-degree oven.
Equipment
Peeler | Mandolin | Saucepan | Mesh strainer | 3.5 QT casserole | Grater | Liquid measuring cup | Measuring spoons
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Sweet Potato Gratin with Rosemary and Sage
Ingredients
- 2 cups heavy cream (plus more as needed)
- 2 sprigs rosemary
- 1 bunch sage ((8-10 leaves))
- ½ teaspoon salt
- ½ teaspoon black pepper
- 2 large russet potatoes
- 2 large sweet potatoes
- ⅓ cup grated Parmesan cheese
Instructions
- Preheat the oven to 400 degrees.
- Add the heavy cream, rosemary, sage, salt and pepper to a small saucepan. Warm the cream slowly over low heat.
- Meanwhile, peel the potatoes and slice them into thin slices approx ⅛-inch thick. A mandolin works well for this but a sharp knife can also be used.
- 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. (Note 1) 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.
Notes
- Thicker-sliced potatoes will take longer to cook. Also, the size of the baking dish can affect baking time as well.
- Cut the potatoes into thin slices. Uniformly sliced potatoes will ensure even cooking. A mandolin is a useful tool for making easy work of slicing potatoes in thin slices. If you don't have a mandolin, a sharp knife can also be used. Thinner sliced potatoes will cook faster than thicker ones.
- Infuse the cream with fresh herbs. I absolutely love fresh rosemary and sage and infusing the cream with these flavors take these potatoes over the top. Don't skip this step!
- To make-ahead, cook, then cool completely. Cover and refrigerate. To reheat, do so covered, in a 350-degree oven.
Nutrition
Nutritional information is an estimate and will vary depending upon the exact amounts and specific ingredients used.
This post was originally published November 2019 and has been updated.
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