This sweet potato gratin is the ultimate cozy side dish. Layers of tender sweet potatoes, melted Graviera (or Gruyère) cheese, and crispy prosciutto bake together into something irresistibly creamy, savory, and a little bit sweet. It’s simple to make, beautifully rustic, and perfect for any holiday table.

If you’re a fan of our delicious Sweet Potato Gratin, you’re in for a treat with our Fig Tart With Phyllo, Phyllo Cup Appetizers, and Roasted Cabbage with Bacon, Raisins, and Garlic!

Close up of sweet potato au gratin with prosciutto and fresh herbs on top.

Overview

Why you will love sweet potato gratin

Sweet meets savory – The combination of caramelized sweet potatoes, nutty Gruyère, and salty prosciutto creates the perfect balance of flavors—comforting yet sophisticated.
Aromatic and cozy – The cream simmers gently with garlic, cloves, nutmeg, and fresh herbs, filling your kitchen with a warm, holiday scent that feels like Christmas in a dish.
Simple yet elegant – Easy to prepare ahead and bake just before serving, it’s ideal for stress-free entertaining.
A crowd-pleaser – Everyone loves a gratin, and this one stands out for being more savory and flavorful than traditional sweet potato casseroles.
Perfect for the holidays – It’s golden, bubbly, and pairs beautifully with roasted meats, turkey, or even a festive vegetarian spread.

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The cover of the Greek foodie holiday cookbook, Greek Feast for the holidays features bowls of Greek dips surrounded with pitas and crudités.

A baking pan with sweet potato au gratin and a gold serving utensil and a piece served on a green plate.

Here is what you need.

Sweet potatoes – Use any variety you like. Mixing red and purple sweet potatoes creates a gorgeous, colorful dish that looks stunning on the table.
Graviera cheese (or Gruyère) – This nutty, slightly sweet cheese melts beautifully into the layers. If you can find Greek Graviera, give it a try, it’s a delicious Cretan version of Gruyère.
Prosciutto cubetti – These small, thick cubes of prosciutto are perfect for this gratin and save you the trouble of cutting thin slices. They’re easy to find in most supermarkets. You can also substitute with pancetta or bacon for a similar savory kick.
Butter – I prefer salted butter for extra flavor, but you can use your favorite.
Heavy cream – Rich and luscious, it binds the layers together. For a lighter version, substitute half-and-half or whole milk.
Eggs – Fresh, organic, and free-range if possible, always worth it for flavor and texture.
Fresh sage and thyme – Classic holiday herbs that infuse the gratin with cozy, aromatic notes. Dried herbs work too if that’s what you have.
Cloves and ground nutmeg – These warming spices add a subtle sweetness that makes the cream mixture smell like Christmas custard.
Garlic – Just a touch adds depth and rounds out the flavors.
Sea salt and freshly ground pepper – Essential for balancing the sweetness of the potatoes and the richness of the cheese.

Detailed measurements and instructions can be found on the recipe card at the bottom of the page.

How to make this sweet potato au gratin

Sauce pan with cream, fresh herbs and spices.

Preheat the oven to 400°F (200°C). In a medium pot, combine the cream, a few sage leaves, cloves, thyme sprigs, minced garlic, ground nutmeg, and a pinch of sea salt. Bring to a gentle simmer and cook for about 10 minutes, until slightly reduced and fragrant. Strain the mixture through a fine sieve to remove the herbs and cloves.

Eggs being beaten and adding cream to them.

In a large bowl, lightly whisk the eggs. Slowly pour in the warm cream while whisking constantly so the eggs don’t scramble. Mix well and set aside.

Four images. One, a buttered pan. Two, the pan with a layer potatoes and egg, cheese, herbs, prosciutto mix. Three, similar layer as two. Four, final layer of potatoes, cheese, egg and prosciutto.

Generously butter your baking dish (approximately 10.5″ x 7.5″). Sprinkle a little grated Graviera over the bottom to create a flavorful base. (image 1)
Layer the sweet potatoes: Arrange a layer of thinly sliced sweet potatoes, slightly overlapping. Season with a pinch of salt and freshly ground pepper. Pour over ⅓ of the cream-egg mixture, then sprinkle ⅓ cup Graviera and 1 tablespoon prosciutto cubetti on top. (image 2)
Repeat the layering process, adding potatoes, seasoning, cream mixture, cheese, and prosciutto two more times, ending with the final layer of potatoes, the remaining cream mixture, and toppings. (images 3-4)
Cover the dish with a buttered sheet of foil and bake for about 40 minutes, until the potatoes are tender when pierced with a knife.

A half baked sweet potato au gratin before going back to the oven.

Remove the foil, sprinkle the top with the remaining Graviera, and bake uncovered for another 25–30 minutes, until the gratin is golden brown and bubbling.

Suggestions & Substitutions

Slice evenly: Use a mandoline or sharp knife to slice the sweet potatoes uniformly, this ensures they cook evenly and layer beautifully.
Warm the cream gently: Don’t let it boil too hard; gentle simmering helps infuse the herbs and keeps the cream silky.
Gruyère vs. Graviera: If you can find Greek Graviera, try it! It adds a distinct nutty flavor and a touch of Greek authenticity.
Make ahead: Assemble the gratin a few hours before baking. Cover and refrigerate, then bake just before serving.
For a crispier top: Broil for 2–3 minutes at the end, but keep an eye on it so it doesn’t burn.
Let it rest: Give it 10–15 minutes after baking. This allows the custard to set and makes serving easier.

A sweet potato casserole and two serving utensils.

Serving suggestions

This sweet potato gratin makes a wonderful side dish for both everyday dinners and festive occasions. It’s rich, aromatic, and pairs beautifully with roasted meats and fresh salads.

Holiday mains: Serve alongside roast herb butter turkey, pork pot roast, or roasted leg of lamb for a show-stopping holiday table.
Simple pairings: It also complements grilled chicken skewers, baked salmon, or a crispy green salad with lemon vinaigrette for a lighter meal.
Vegetarian spread: Skip the prosciutto for a meat-free version and pair it with roasted vegetables or a hearty lentil salad.
Make it part of a Greek-style feast: Add maroulosalata, Greek lemon potatoes, and a savory cheese pie (tiropita) to create a full Mediterranean menu.

FAQs about ssweet potato au gratin

es! You can assemble the gratin a few hours before baking, cover it tightly with foil, and refrigerate. When ready to serve, bake as directed. If baking straight from the fridge, add about 10 extra minutes to the cooking time.

Absolutely. Simply omit the prosciutto or replace it with sautéed mushrooms, caramelized onions, or sun-dried tomatoes for extra depth of flavor.

If Graviera or Gruyère isn’t available, try Emmental, Comté, or sharp white cheddar.

It’s up to you! The peel adds texture and nutrients. If you prefer a smoother gratin, peel them first; if you like a rustic look, leave the skins on.

Storage and reheating

Refrigerate: Store leftovers in an airtight container in the refrigerator for up to 3 days.
Reheat: Warm individual portions in the microwave or reheat the whole dish in a 350°F (175°C) oven, covered with foil, until heated through (about 20 minutes).
Avoid drying out: Add a splash of milk or cream before reheating to restore the creamy texture.
Not ideal for freezing: The custard and cheese can separate once thawed, so this gratin is best made fresh or enjoyed within a few days.

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