Sweet Potato Gratin
Sweet Potato Gratin is a cozy, comforting dish that combines tender layers of sweet potatoes with creamy goodness and a golden, cheesy crust. It’s a perfect mix of sweet and…
Tip: save now, cook later.Sweet Potato Gratin is a cozy, comforting dish that combines tender layers of sweet potatoes with creamy goodness and a golden, cheesy crust. It’s a perfect mix of sweet and savory that feels like a warm hug on a plate. The soft slices of sweet potato cook down just right, soaking up the rich sauce and toppings, making each bite smooth and flavorful.
I love making this gratin when I want something simple but special. One tip I’ve picked up is to slice the sweet potatoes evenly so they cook through beautifully and layer nicely. The combination of cream and cheese feels fancy but is actually super easy to put together. It’s the kind of dish that looks impressive but doesn’t stress me out in the kitchen, which is always a win in my book.
This gratin is wonderful served alongside a roast or even just a fresh salad. I like to make it for family dinners or holiday meals because it’s something everyone enjoys and it brings a little extra warmth to the table. Plus, leftovers taste even better the next day if you have any! It’s become one of those dishes I rely on for comfort and smiles every time I make it.
Key Ingredients & Substitutions
Sweet Potatoes: Thinly sliced sweet potatoes create tender layers. Use a mandoline slicer if you have one for even slices. If sweet potatoes aren’t available, try using Yukon gold potatoes for a different twist.
Cream & Milk: The mix of heavy cream and milk gives richness without being too heavy. For a lighter version, substitute half the cream with evaporated milk or use all milk, but the gratin will be less creamy.
Gruyère Cheese: Gruyère melts smoothly and adds a mild nutty flavor. If you can’t find it, Fontina or sharp white cheddar make tasty alternatives. Parmesan on top can add extra crispiness too.
Herbs & Spices: Fresh thyme adds great aroma, but dried thyme works just fine too. Nutmeg is a small touch that brings warmth; don’t skip it. Fresh sage on top adds a lovely earthy note.
How Can I Get Perfectly Cooked, Tender Sweet Potato Layers?
The key is slicing and layering evenly. Here’s what helps:
- Slice potatoes uniformly thin (about 1/8 inch thick) so they cook evenly and soak up the cream well.
- Layer slices with slight overlap for even cooking and a beautiful stacked look.
- Pour warm cream mixture over each layer to help soften the potatoes as they bake.
- Cover with foil for the first part of baking to trap steam, then uncover at the end to brown the top.
After baking, let the gratin rest for 10 minutes. This lets the cream thicken and the layers set, making it easier to slice and serving a smooth texture. I find this resting step makes a big difference!
Equipment You’ll Need
- Mandoline slicer – makes slicing sweet potatoes thin and even, so they cook perfectly.
- 9×13 inch baking dish – the ideal size for even cooking and layering your gratin.
- Medium saucepan – for warming the cream, milk, and seasonings gently without boiling.
- Grater – to shred cheese finely so it melts evenly throughout and on top.
- Aluminum foil – to cover the dish during baking and keep the moisture in while the potatoes soften.
Flavor Variations & Add-Ins
- Add cooked crumbled bacon or pancetta for a salty, smoky crunch that pairs well with sweet potatoes.
- Mix in caramelized onions between layers to add sweetness and depth.
- Use goat cheese or feta instead of Gruyère for a tangy, creamy twist.
- Sprinkle chopped fresh rosemary or sage for an earthy herb flavor that brightens the dish.
Sweet Potato Gratin
Ingredients You’ll Need:
- 3 large sweet potatoes (about 2 pounds), peeled and thinly sliced
- 2 cups heavy cream
- 1 cup whole milk
- 3 cloves garlic, minced
- 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried thyme)
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1/4 teaspoon ground nutmeg
- 1 1/2 cups Gruyère cheese, grated (or Fontina/sharp white cheddar)
- 2 tablespoons unsalted butter, for greasing the dish
- Fresh sage or thyme sprigs (optional, for garnish)
How Much Time Will You Need?
Getting this dish ready and baked takes about 15 minutes to prepare plus around 55 minutes baking time. Add 10 extra minutes to let the gratin rest before serving. So in total, plan for about 1 hour and 20 minutes from start to finish.
Step-by-Step Instructions:
1. Prepare the Oven and Dish
Preheat your oven to 375°F (190°C). Butter your 9×13 inch baking dish nice and well to stop the gratin from sticking.
2. Make the Cream Mixture
In a medium saucepan on low heat, warm the heavy cream, milk, minced garlic, thyme, salt, pepper, and nutmeg. Heat it gently until just about to simmer—don’t boil it! Then take it off the heat.
3. Layer the Sweet Potatoes
Start by laying down a layer of sweet potato slices in the dish, overlapping a little so they fit nicely. Pour some of the warm cream mix over them, just enough to coat but not drown.
4. Add Cheese and Repeat
Sprinkle some grated Gruyère on top of that layer. Then keep layering potatoes, cream mixture, and cheese until you’ve used everything. Finish with a cheese layer on top.
5. Bake Covered and Uncovered
Cover the dish with foil and bake for 30 minutes. Then take off the foil and bake another 25-30 minutes uncovered, until the top turns golden and the sweet potatoes are tender when poked with a fork.
6. Rest, Garnish, and Serve
Let your gratin rest for 10 minutes before serving. This helps it set and slice better. If you like, decorate with fresh sage or thyme sprigs and serve warm!
Can I Use Frozen Sweet Potato Slices?
It’s best to use fresh sweet potatoes for this recipe to get the right texture. If you only have frozen slices, thaw them completely and pat dry to remove excess moisture before layering.
Can I Prepare Sweet Potato Gratin Ahead of Time?
Yes! Assemble the gratin and cover it tightly with foil or plastic wrap, then refrigerate for up to 24 hours. When ready, bake as directed, adding a few extra minutes if baking from cold.
How Should I Store Leftovers?
Store any leftover gratin in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave until warmed through.
What Are Some Good Cheese Substitutes?
If you don’t have Gruyère, Fontina, sharp white cheddar, or even a combination of mozzarella and Parmesan work well to give that melty, golden top with great flavor.