At Camélia in LA—one of our Best New Restaurants of 2025—chef Charles Namba reimagines comfort classic sweet potato gratin through a French-Japanese lens. “When I was little,” says Namba, “my mom prepared Japanese sweet potatoes by cutting one in half, shoving cold butter between the slices, and microwaving it.” Inspired by this trick, Namba built a dish as nostalgic as it is modern.
Instead of the thin orange layers of potatoes found in most sweet potato gratin recipes, his version starts with large chunks of cream-colored Japanese sweet potatoes, boiled until tender and lightly mashed with salty-sweet miso butter. Slightly sweeter than other varieties, Japanese sweet potatoes have a naturally starchy, buttery texture that adds luxurious body without extra fuss. (In a pinch, standard sweet potatoes or garnet yams will work just fine.) And skipping the mandoline slicer and all that layering means minimal prep time.
You’ll spread the potato mixture into a casserole dish before finishing it off with a scattering of cheese and a final flourish of chives and nori. Namba’s sweet potato gratin delivers golden brown, crispy edges with layers of savory umami and creamy richness, making it an easy, flavor-packed side dish worthy of any holiday feast.
Chef’s Note: Japanese sweet potatoes can be found in most well-stocked grocery stores or international markets. They have a slightly sweeter flavor than their orange-hued counterparts and boast a starchier, denser texture; if you can’t get your hands on them, a standard sweet potato will work just fine.
Recipe information
Total Time
1 hour 30 minutes
Yield
6–8 servings
Ingredients
1
3
8
2
1
1
3
2
2
Need to make a substitution?
Preparation
Step 1
Cook 1 dried bay leaf and 3 lb. Japanese sweet potatoes (about 4 large or 6 small) or other sweet potatoes, peeled, cut into 1" pieces, in a large pot of boiling salted water until potatoes are fork-tender, 20–25 minutes. Drain, reserving 1 cup cooking liquid; discard bay leaf. Set aside; reserve pot.
Step 2
Meanwhile, place a rack in upper third of oven and preheat to 400°. Lightly coat an 8x8" baking dish or 1½-qt. oval baking dish with unsalted butter. Stir together 2 Tbsp. white miso, 1 Tbsp. honey, and 8 Tbsp. unsalted butter, room temperature, in a small bowl until smooth. Transfer 1 Tbsp. miso butter to another small bowl; set aside.
Step 3
Melt 2 Tbsp. (heaping) miso butter in reserved pot over medium heat. Add 1 medium shallot, halved, thinly sliced, and 3 small sprigs thyme, leaves picked; cook, stirring often with a heatproof rubber spatula, until shallot is softened, about 4 minutes. Remove pot from heat. Add reserved sweet potatoes and remaining miso butter from first bowl (a little less than 5 Tbsp.) and toss to coat. Mash sweet potatoes with spatula, adding a splash of sweet potato cooking liquid as needed, until mostly creamy with some intact pieces remaining (think halfway to mashed potatoes). Season with salt and freshly ground pepper.
Step 4
Spread sweet potato mixture into an even layer in prepared dish. Top with 2 oz. Fontina cheese, coarsely grated (about ½ cup), and 2 oz. Gruyère, coarsely grated (about ½ cup); dot with dollops of reserved 1 Tbsp. miso butter. Bake until cheese is melted, 15–20 minutes.
Step 5
Heat broiler (you can leave gratin in oven). Broil just until cheese is melted and browned in spots, 1–2 minutes. (Watch carefully as the cheese can go quickly from browned to burnt.) Remove gratin from oven; sprinkle aonori (dried powdered seaweed) or crushed seasoned toasted nori snacks and thinly sliced chives on top.