Sweet Potato Gratin with Cream and Thyme
Sweet Potato Gratin with Cream and Thyme is a cozy and comforting dish that's perfect for any time you want something rich but not too fancy. The sweet potatoes get…
Tip: save now, cook later.Sweet Potato Gratin with Cream and Thyme is a cozy and comforting dish that’s perfect for any time you want something rich but not too fancy. The sweet potatoes get soft and tender, soaking up the creamy sauce, while the thyme adds a gentle, earthy flavor that balances everything out. Each slice comes out with a golden, bubbly top that’s just irresistible.
I love making this gratin when I want to impress family or friends without spending too long in the kitchen. It’s one of those recipes where you can prep everything ahead of time, pop it in the oven, and relax while it cooks. The smell of thyme and cream filling the air is a sign that something good is coming!
My favorite way to serve this dish is alongside a simple green salad or roasted chicken. It feels like such a thoughtful combination, and everyone always asks for seconds. Plus, leftovers the next day are just as delicious—sometimes I even eat it cold for a quick snack. It’s a warm and satisfying dish that feels like a little celebration on your plate.
Key Ingredients & Substitutions
Sweet Potatoes: Choose firm and fresh sweet potatoes with smooth skin for even cooking and the best texture. If you prefer, you can substitute with regular potatoes or a mix of sweet and Yukon gold potatoes for a milder flavor.
Heavy Cream: Heavy cream gives the gratin its creamy, rich texture. For a lighter version, try half-and-half or full-fat coconut milk, but the dish won’t be quite as rich or silky.
Fresh Thyme: Fresh thyme adds a subtle, earthy note that pairs beautifully with sweet potatoes. Dried thyme works in a pinch, but use less—about 1 teaspoon. You can also try rosemary or sage if you want a slightly different herbal flavor.
Cheese (Optional): Parmesan or Gruyère adds a crispy, golden topping and extra depth. If you want it dairy-free, skip the cheese or try a sprinkle of nutritional yeast for a cheesy taste without the dairy.
How Do I Get the Sweet Potatoes Tender and the Top Perfectly Golden?
The key to this gratin is layering and baking it slowly to let the cream soak in and the potatoes soften without drying out. Here’s how to do it right:
- Slice evenly: Cut sweet potatoes about 1/4 inch thick. This helps them cook through at the same time and look nice in layers.
- Layer with cream: Pour the cream mixture over each layer to keep potatoes moist and flavorful.
- Cover for initial baking: Cover the dish with foil while baking to trap steam and cook potatoes gently.
- Finish uncovered: Remove foil in the last 15-20 minutes to let the top brown and become slightly crispy.
- Rest before serving: Letting it sit for 10 minutes thickens the cream sauce, making it easier to slice and serve.
Equipment You’ll Need
- Medium gratin or baking dish – perfect size for layering sweet potatoes and baking evenly.
- Sharp knife – helps you cut thin, even sweet potato slices for consistent cooking.
- Cutting board – provides a safe, sturdy surface for slicing the potatoes.
- Mixing bowl – to combine the cream, herbs, and seasoning easily.
- Aluminum foil – to cover the dish during baking and keep the potatoes moist.
- Measuring cups and spoons – for accurate cream and seasoning amounts.
Flavor Variations & Add-Ins
- Add crumbled cooked bacon or pancetta for a smoky, salty boost that pairs well with sweet potatoes.
- Mix in shredded Gruyère or sharp cheddar for a cheesier, richer gratin.
- Try fresh sage or rosemary instead of thyme for a woodsy twist on the herb flavor.
- Include thin slices of onion or leeks between the layers for a mild sweetness and texture contrast.
Sweet Potato Gratin with Cream and Thyme
Ingredients You’ll Need:
Main Ingredients:
- 3 large sweet potatoes (about 2 pounds), peeled and sliced into 1/4-inch rounds
- 1 1/2 cups heavy cream
- 2 garlic cloves, minced
- 2 tablespoons fresh thyme leaves (plus a few sprigs for garnish)
- 1 teaspoon fresh sage, chopped (optional)
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1/4 teaspoon ground nutmeg (optional)
- 1 tablespoon unsalted butter, for greasing the baking dish
- 1/2 cup grated Parmesan cheese or Gruyère cheese (optional, for a more golden top)
How Much Time Will You Need?
This recipe takes about 15 minutes to prepare and around 50-60 minutes for baking. After baking, you’ll want to let the gratin rest for 10 minutes before serving. So, plan for roughly 1 hour and 15 minutes total from start to finish.
Step-by-Step Instructions:
1. Prepare Your Oven and Dish:
Preheat your oven to 375°F (190°C). Lightly butter a medium-sized gratin or casserole dish, making sure the butter coats the bottom and sides to prevent sticking.
2. Slice the Sweet Potatoes:
Peel the sweet potatoes and slice them into 1/4-inch thick rounds. Try to keep the slices even, so they cook through evenly.
3. Mix the Cream and Seasonings:
In a mixing bowl, combine the heavy cream, minced garlic, fresh thyme leaves, chopped sage (if you’re using it), salt, pepper, and nutmeg. Stir everything together well so all the flavors are mixed.
4. Layer the Sweet Potatoes:
Arrange a layer of the sweet potato slices neatly in the prepared baking dish. Slightly overlap the slices to cover the base.
5. Add Cream and Cheese:
Pour some of the cream mixture over the first layer to coat evenly. If you love cheesy tops, sprinkle a little grated Parmesan or Gruyère on top.
6. Repeat Layers:
Keep layering sweet potatoes and cream mixture until you’ve used all the slices. Finish with the cream and cheese on top.
7. Add the Herb Garnish:
Place a few sprigs of fresh thyme on top for extra aroma and a pretty presentation.
8. Bake Covered:
Cover the dish loosely with aluminum foil and bake it in the oven for 35-40 minutes. Covering helps the potatoes cook gently with steam.
9. Bake Uncovered for a Golden Top:
Remove the foil and bake for another 15-20 minutes. This will let the top become golden, bubbly, and a little crispy.
10. Rest and Serve:
Take the gratin out of the oven and let it rest for about 10 minutes. This lets the cream thicken a bit and makes it easier to serve. Enjoy it warm as a cozy side dish!
Can I Use Frozen Sweet Potatoes for This Gratin?
It’s best to use fresh sweet potatoes for even cooking and the best texture. If using frozen, make sure they are fully thawed and patted dry to avoid excess moisture that can make the gratin watery.
Can I Make Sweet Potato Gratin Ahead of Time?
Absolutely! Assemble the gratin and cover it tightly, then refrigerate for up to 24 hours before baking. Add a few extra minutes to the baking time if baking straight from the fridge.
How Should I Store Leftovers?
Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently in the oven or microwave until warmed through.
Can I Substitute Heavy Cream with Something Lighter?
You can use half-and-half or whole milk for a lighter version, but the gratin will be less rich and creamy. Adding a bit of flour or cornstarch can help thicken the sauce if needed.
