This Sweet Potato & Cranberry Gratin has become one of my favorite dishes to bring to family dinners and holiday tables. I first developed this combination on an autumn weekend when I wanted something that felt festive without being overly fussy. The tart pop of fresh cranberries against the mellow, caramel-like sweetness of the potatoes creates a balanced bite, while the Gruyère gives a lightly nutty, savory finish that makes people reach for seconds. It’s the kind of dish that warms the kitchen with a cozy aroma and invites conversation while it finishes in the oven.

I remember the first time I served this at a small Thanksgiving—my cousin, who usually prefers plain mashed potatoes, went back for thirds and asked for the recipe on the spot. The texture is key: tender but not mushy slices of sweet potato, a silky custard formed by the cream and brown sugar, and a crunchy breadcrumb and cheese top that browns beautifully at 375°F. I developed the timing to ensure the potatoes cook through without falling apart, and the cranberries retain a pleasant burst of acidity. This recipe is straightforward, comforting, and flexible enough to fit weeknight dinners or holiday spreads.

Ingredients

• Sweet potatoes (2 pounds): Choose firm, evenly shaped sweet potatoes for uniform slicing and even cooking. I prefer garnet or jewel varieties for their deep orange color and natural sweetness. If you buy from a farmer’s market, smaller roots tend to have better texture and fewer woody cores.
• Fresh cranberries (1 cup): Look for bright, firm cranberries in a single layer—avoid any that are soft or shriveled. The fresh berries give a lively tartness that balances the dish; frozen can be used in a pinch but thaw and drain excess liquid first.
• Heavy cream (1 cup): Use full-fat heavy cream for the richest custard and the best mouthfeel. Brands with minimal additives produce a cleaner flavor; heavy cream also helps the top brown and the filling set without becoming grainy.
• Gruyère cheese, shredded (1 cup): Authentic Swiss Gruyère melts smoothly and adds a nutty, slightly sweet complexity. Emmental or a mild fontina can substitute, but the flavor will shift slightly lighter or milder.
• Breadcrumbs (1/2 cup): Plain or panko breadcrumbs work—panko yields a lighter, crunchier crust while regular breadcrumbs give a denser finish. For added flavor, use seasoned breadcrumbs or toast plain crumbs with a little butter first.
• Brown sugar (1/4 cup): Light or dark brown sugar will both work; dark adds deeper molasses notes. The sugar lightly caramelizes with the cream to create a gently sweet base that complements savory cheese.
• Cinnamon (1 teaspoon): Ground cinnamon warms the dish and pairs beautifully with sweet potato. If you like a little more depth, add 1/4 teaspoon of ground nutmeg or allspice.
• Salt and pepper (to taste): Kosher salt and freshly ground black pepper help to balance sweetness and round the flavors. Start with 1/2 teaspoon salt in the cream mixture and adjust from there when tasting before baking.

Instructions

Preheat and prep: Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish with butter or neutral oil so the gratin doesn’t stick and the edges brown evenly. Arrange tools and ingredients so that the layering is smooth and continuous when the potatoes are drained. Parboil sweet potatoes: Place the peeled and sliced sweet potatoes in a large pot and cover with cold water. Bring to a boil, then reduce to a simmer and cook until tender when pierced with a fork, about 10–15 minutes depending on slice thickness. Do not overcook; slices should hold their shape for clean layering. Layer first half: Drain the potatoes well and pat dry if they’re still moist. Arrange half of the slices in an even layer in the prepared baking dish, slightly overlapping for structure. Scatter half of the fresh cranberries over the potato layer. Mix and pour custard: In a medium bowl, whisk together the heavy cream, brown sugar, cinnamon, 1/2 teaspoon kosher salt, and a few grinds of black pepper until the sugar dissolves. Pour half of this mixture evenly over the first potato and cranberry layer so the liquid settles around but not completely submerging the slices. Repeat layers: Arrange the remaining sweet potato slices in the dish, add the remaining cranberries, and pour the remaining cream mixture on top. Press gently so the cream seeps between layers but avoid crushing the slices. Top and bake: Sprinkle the shredded Gruyère evenly over the top, then scatter breadcrumbs to create a protective crunchy layer. Bake in the preheated oven for 30–35 minutes or until the top is golden brown, the cheese is melted and bubbly, and the custard is set. If the top browns too quickly, tent with foil for the last 10 minutes. Rest and serve: Let the dish cool for 5–10 minutes to allow the custard to settle; this makes slicing cleaner and the texture richer. Serve warm as a side or small main with a crisp salad or roasted protein.

Storage Tips

To store leftovers, cool the gratin to room temperature (no more than two hours at room temperature), then transfer to an airtight container or cover the baking dish tightly with foil. Refrigerate for up to four days; quality remains best within two days. For longer storage, freeze in a shallow, freezer-safe container for up to three months. Thaw overnight in the refrigerator before reheating. To reheat, cover with foil for the first 15 minutes at 350°F, then remove foil for a final 8–10 minutes to crisp the top. If reheating from frozen, allow an additional 20–30 minutes and tent with foil if the top browns too quickly.

Ingredient Substitutions

If you need to adapt ingredients, try these swaps and expect minor flavor and texture changes: use half-and-half instead of heavy cream for a lighter custard (the filling will be a touch less rich). Substitute sharp cheddar for Gruyère if you prefer a more pronounced tang; fontina or Monterey Jack yield a milder melt. For a gluten-free option, replace breadcrumbs with crushed gluten-free crackers or toasted, chopped nuts like pecans for extra crunch. If fresh cranberries aren’t available, use 3/4 cup dried cranberries rehydrated in warm water for 10 minutes—drain well and reduce brown sugar by a tablespoon to account for added sweetness.

Serving Suggestions

This gratin pairs beautifully with roasted turkey or chicken, grilled pork chops, or a bright green salad with a citrus vinaigrette to cut the richness. For a brunch approach, serve alongside scrambled eggs or a frittata; garnish with chopped fresh parsley or a sprinkle of flaky sea salt to highlight the flavors. For holiday tables, present in an attractive casserole dish and add a handful of toasted pecans on top just before serving for visual contrast and crunch. Small portions also work well as an hors d’oeuvre on toasted baguette slices.

Cultural Background

Rooted in European gratin techniques, this dish borrows the French idea of layering thinly sliced vegetables with cream and cheese, then baking until golden. Sweet potatoes are a staple in North American autumn and winter cooking, often appearing in casseroles and pies. Adding cranberries reflects a New World pairing—native North American berries that have long been used fresh, dried, or as sauces—creating a hybrid that feels both traditional and contemporary. The result is an approachable, cross-cultural comfort dish that leans on classic techniques with seasonal American ingredients.

Seasonal Adaptations

In late fall and winter, use fresh cranberries and a pinch of nutmeg for warming depth. In spring or summer, swap cranberries for halved fresh cherries or roasted peaches and reduce brown sugar slightly for a brighter finish. For Thanksgiving or Christmas, add 1/4 cup maple syrup to the cream for a deeper autumnal profile. For a lighter summer version, use low-fat cream and omit breadcrumbs, finishing with a scattering of fresh herbs like thyme and chives after baking.

Success Stories

Readers often tell me this is the dish that persuaded their family to try sweet potatoes beyond the usual mash. One friend wrote that she served it at a holiday potluck and strangers asked for the recipe at the end of the evening. Another reader said doubling the recipe for a church luncheon was a hit—she added toasted pecans on top and the crunchy contrast had guests coming back for seconds. These notes are a reminder that simple ingredient harmony can make a dish memorable.

Meal Prep Tips

If you’re prepping ahead, parboil the sweet potato slices and cool completely, then assemble the gratin up to 24 hours in advance and keep it covered in the refrigerator. Bring it to room temperature for 30 minutes before baking to ensure even cooking, then bake as directed—add an extra 5–10 minutes if it’s chilled. For portable meals, bake in disposable aluminum pans and transport covered; reheat in a 350°F oven for 20–25 minutes until warmed through. Portion into individual ramekins for grab-and-go lunches or catered events.

At its heart, this gratin is a celebration of texture and balance: creamy, sweet, tart, and crisp. Whether you’re serving it at a quiet family dinner or a festive holiday table, it’s a dish that invites conversation, seconds, and easy tweaks to make it your own. Give it a try the next time you want a comforting side that feels a little special.