Sweet Potato Gratin with Cream and Thyme
Sweet Potato Gratin with Cream and Thyme is a cozy, delicious side dish that feels like a warm hug on a plate. Thin slices of sweet potato are layered with…
Tip: save now, cook later.Sweet Potato Gratin with Cream and Thyme is a cozy, delicious side dish that feels like a warm hug on a plate. Thin slices of sweet potato are layered with rich cream and fresh thyme, creating soft, tender bites that have just the right touch of herbal flavor and creaminess. The top gets golden and a little crispy, making each forkful a perfect mix of smooth and crunchy textures.
I love making this gratin when I want something special but not too complicated. The thyme adds a lovely fragrance that balances out the sweetness of the potatoes, and the cream makes everything so rich and comforting. It’s one of those dishes where the ingredients come together in the simplest way, but the result feels fancy and thoughtful.
This gratin works beautifully alongside roasted meats or a simple green salad. I usually serve it at family dinners because it’s a crowd-pleaser and easy to prepare ahead. Plus, leftovers taste just as good the next day, which is always a bonus in my book!
Key Ingredients & Substitutions
Sweet Potatoes: Use firm, fresh sweet potatoes for the best texture. If you want a different flavor, try Yukon Gold potatoes, but keep in mind they’ll be less sweet.
Heavy Cream: This makes the dish creamy and rich. For a lighter version, use half-and-half or a mix of milk and cream, but the texture will be less luxurious.
Thyme: Fresh thyme adds a fragrant, slightly earthy note. If you don’t have fresh, dried thyme works well—just use less (around 1 teaspoon).
Cheese (Optional): Gruyère or cheddar adds nice flavor and a golden top. For a dairy-free option, skip the cheese or use a plant-based cheese, but the flavor will be milder.
How Do You Get Thin, Even Sweet Potato Slices for Perfect Baking?
Thin, uniform slices cook evenly and blend well in the gratin. Here’s how:
- Use a sharp knife or a mandoline slicer to get thin, consistent slices (around 1/8 inch thick).
- Take your time peeling and slicing carefully to avoid uneven thickness.
- Try to slice all potatoes to about the same thickness to ensure even cooking throughout the dish.
This helps each layer cook properly, preventing any tough or overly soft spots in the gratin.
Equipment You’ll Need
- Mandoline slicer – makes slicing sweet potatoes thin and even quick and safe.
- Medium saucepan – warms the cream and infuses it with garlic and thyme gently.
- Sharp knife – if you don’t have a mandoline, a good knife helps slice potatoes thinly.
- Heatproof baking dish (about 8×8 inches or similar) – perfect size for layering and baking evenly.
- Aluminum foil – to cover the dish during baking and keep moisture in.
Flavor Variations & Add-Ins
- Add crumbled cooked bacon for a smoky, salty touch that pairs well with the creamy potatoes.
- Stir in grated Parmesan or switch Gruyère to Parmesan for a sharper, nuttier flavor.
- Mix some sautéed onions or shallots into the cream for extra sweetness and depth.
- Add a pinch of smoked paprika or cayenne pepper for a subtle spicy kick.
Sweet Potato Gratin with Cream and Thyme
Ingredients You’ll Need:
For the Gratin:
- 2 pounds sweet potatoes, peeled and thinly sliced
- 1 ½ cups heavy cream
- 2 cloves garlic, minced
- 1 tablespoon fresh thyme leaves (or 1 teaspoon dried thyme)
- ½ teaspoon salt, or to taste
- ¼ teaspoon freshly ground black pepper
- ¼ teaspoon ground nutmeg (optional)
- 1 cup grated Gruyère or sharp cheddar cheese (optional)
- Butter or oil for greasing the baking dish
How Much Time Will You Need?
Total time is about 1 hour and 15 minutes. It takes around 15 minutes to prepare the potatoes and cream mixture, then about 1 hour to bake the gratin—40 minutes covered and another 20-25 minutes uncovered to get a golden, bubbly top. Let it rest 10 minutes before serving.
Step-by-Step Instructions:
1. Prepare Your Oven and Baking Dish:
Preheat your oven to 375°F (190°C). Grease a medium-sized baking dish with butter or oil to prevent sticking and to add flavor.
2. Slice the Sweet Potatoes:
Peel your sweet potatoes and slice them into even, thin rounds about 1/8 inch thick. Using a mandoline slicer makes this easier and safer, but a sharp knife works fine if careful.
3. Make the Cream Mixture:
In a small saucepan, gently warm the heavy cream with minced garlic, fresh thyme leaves, salt, pepper, and nutmeg if you like. Heat just until the cream is fragrant and ingredients are combined—don’t let it boil.
4. Layer the Gratin:
Arrange a layer of sweet potato slices in the bottom of your baking dish, slightly overlapping them. Pour a little of the cream mixture over the potatoes to coat evenly. If you’re adding cheese, sprinkle some on top. Repeat layering sweet potatoes, cream, and cheese until everything is used, finishing with cream on top.
5. Bake Covered, Then Uncovered:
Cover the dish with aluminum foil and bake for 40 minutes. Then remove the foil and bake an additional 20-25 minutes until the potatoes are tender and the top is golden and bubbling.
6. Rest and Serve:
Let your gratin rest for about 10 minutes after baking. This helps the cream thicken up and the flavors to blend nicely. Garnish with fresh thyme if you like, then serve warm as a comforting, flavorful side dish.
Can I Use Frozen Sweet Potatoes for This Gratin?
It’s best to use fresh sweet potatoes for this recipe because frozen ones can release extra moisture and result in a watery dish. If you only have frozen, thaw them completely and pat dry before slicing and baking.
Can I Prepare the Gratin Ahead of Time?
Yes! You can assemble the gratin up to a day ahead, cover it tightly with foil or plastic wrap, and keep it refrigerated. When ready to bake, just add extra baking time if it’s straight from the fridge.
How Should I Store Leftovers?
Store leftovers in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave until warmed through to keep the creamy texture.
Can I Make This Dish Dairy-Free?
Absolutely! Substitute the heavy cream with full-fat coconut milk or a creamy plant-based alternative, and use dairy-free cheese or omit cheese altogether. The texture might be slightly different but still delicious.
