This gratin quickly became my go-to for holiday gatherings and chilly weeknights. I first developed this combination on a crisp November afternoon when I wanted something that felt festive without being fussy. The contrast between the naturally sweet, velvety sweet potato slices and the bright, slightly tart cranberries creates a balance that keeps each bite interesting. The cream and Gruyère lend a savory, nutty richness while the browned breadcrumbs give a satisfying crunch. I remember serving it next to roast chicken one year; a picky cousin declared it the "best side ever," and it has been requested for every Thanksgiving since.

What makes this dish special is its simplicity and the way pantry and seasonal ingredients come together with minimal fuss. It’s forgiving — the potatoes can be parboiled a touch longer if you prefer them softer, and leftovers reheat beautifully. I often make it ahead, refrigerate, and slip it into the oven an hour before guests arrive so the top goes golden just as everyone sits down. The aroma of cinnamon and brown sugar mingling with melting cheese is one of those kitchen smells that turns guests into instant fans.

Ingredients

• 2 pounds sweet potatoes: Choose firm, evenly shaped tubers for consistent slices. I prefer orange-fleshed varieties for sweetness and color; look for blemish-free potatoes and peel if the skin is tough.
• 1 cup fresh cranberries: Fresh are best for a bright tart pop; if using frozen, do not thaw completely to avoid excess moisture. Fresh cranberries add color and a pleasant counterpoint to the sweetness.
• 1 cup heavy cream: Full-fat cream makes the layers luxuriously silky. You can substitute half-and-half for a lighter creaminess, though the texture will be slightly thinner.
• 1 cup shredded Gruyère cheese: Gruyère melts beautifully and adds a nutty, slightly sweet-savory character. If unavailable, Emmental or a mild Swiss cheese are suitable substitutes.
• 1/2 cup breadcrumbs: Use plain or Panko for extra crunch; toasted breadcrumbs create a crisp topping that contrasts with the soft potatoes.
• 1/4 cup brown sugar: Light or dark brown sugar deepens the caramel notes. If you prefer less sweetness, reduce to 2 tablespoons and taste the cream mixture before pouring.
• 1 teaspoon cinnamon: A warm spice that complements sweet potatoes and cranberries. For extra warmth, add a pinch of ground nutmeg.
• Salt and pepper to taste: Kosher salt and freshly cracked black pepper are recommended. Salt is essential to pull flavors together; start modest and adjust after baking if needed.

Instructions

Preheat and prep: Preheat the oven to 375°F. Grease a 9x13 baking dish with butter or neutral oil. Bring a large pot of salted water to a boil — salted water seasons the potatoes from the inside and helps maintain their texture. Cook the sweet potatoes: Peel and slice the sweet potatoes into 1/4-inch rounds for even cooking. Boil the slices in batches if necessary to avoid overcrowding. Cook until just tender, about 10–15 minutes depending on thickness; they should give easily with a fork but not be mushy, as they will finish cooking in the oven. Layer the first round: Drain the potatoes well on a towel to remove excess water. Layer half of the potato slices in the prepared baking dish, overlapping slightly for even coverage. Scatter half of the cranberries evenly over the potatoes to ensure bursts of tartness in every portion. Make the cream mixture: In a mixing bowl, whisk together the heavy cream, brown sugar, cinnamon, a pinch of salt, and a few grinds of black pepper. Taste the mixture — it should be slightly sweet but balanced. Pour half of the cream mixture evenly over the first layer to moisten the potatoes. Second layer and topping: Repeat with the remaining potatoes and cranberries, then pour the remaining cream mixture over. Sprinkle the shredded Gruyère evenly across the top, followed by breadcrumbs to create a golden crust during baking. Bake and finish: Bake in the preheated 375°F oven for 30–35 minutes, until the top is golden brown and the filling is bubbly. If the top is browning too quickly, tent with foil for the last 10 minutes. Let rest for 5–10 minutes before serving to let the layers settle.

Storage Tips

Store cooled leftovers in an airtight container for up to three days in the refrigerator. For longer storage, freeze in portioned, oven-safe containers for up to three months; leave a small headspace as cream expands when frozen. When reheating from frozen, thaw in the refrigerator overnight, then warm in a 350°F oven covered for 20–30 minutes, removing the cover for the last 8–10 minutes to re-crisp the topping. For best texture, avoid microwaving directly from frozen, as the topping will lose its crunch.

Ingredient Substitutions

If Gruyère is not available, try Emmental, Jarlsberg, or a medium cheddar for a sharper finish. For a lighter version, swap half of the heavy cream with whole milk or evaporated milk, though the sauce will be less glossy. Replace brown sugar with maple syrup (use about 3 tablespoons) for a deeper, woodsy sweetness. If fresh cranberries are out of season, frozen cranberries work well; keep them slightly frozen when layering to avoid extra liquid. For a nutty twist, sprinkle chopped toasted pecans or walnuts into the breadcrumb topping.

Serving Suggestions

Serve warm as a side to roast turkey or chicken, glazed ham, or alongside a lentil or grain-based main for a vegetarian meal. Garnish with chopped fresh parsley or a few finely sliced scallions for color and brightness. For a holiday spread, present it in a shallow dish with a serving spatula so the layers show; the visual effect of orange potato rounds and red cranberries is festive. Pair with a crisp green salad and a tart vinaigrette to cut through the richness.

Cultural Background

Gratins have French origins, traditionally referring to a dish topped with a browned crust of breadcrumbs or cheese. Using sweet potatoes gives this take an American seasonal twist—sweet potato casseroles are long-time staples in U.S. holiday cuisine, while cranberries are quintessentially associated with fall and winter meals. Combining the two borrows the gratin technique from classic French cooking and pairs it with ingredients rooted in North American culinary traditions, making it familiar yet gently elevated.

Seasonal Adaptations

In winter, add orange zest to the cream mixture for a bright citrus lift; in autumn, swap cinnamon for a warming pumpkin spice blend. Spring and summer versions can replace cranberries with thin slices of roasted apricot or tart cherries for a seasonal fruit contrast. For a smoky autumn variation, roast the sweet potato slices before layering and add a pinch of smoked paprika to the cream.

Meal Prep Tips

To make ahead, complete the full assembly up to two days in advance, cover tightly with plastic wrap, and refrigerate. Bring to room temperature for 30 minutes before baking to ensure even cooking. If freezing assembled portions, wrap tightly and bake directly from thawed; add an extra 8–12 minutes to the bake time if needed. Use shallow, individual ramekins for single-serving portions that are easy to reheat for lunches or quick dinners.

There’s a quiet joy in turning simple ingredients into something that feels special—this dish does that in the most approachable way. Whether you bring it to a potluck or tuck it alongside your weeknight roast, it’s sure to become part of the rotation.