This rippled sweet potato gratin is a refined take on the classic comfort dish, with ultra-thin sweet potato slices folded into soft, sculptural layers and baked in garlicky light cream cheese with thyme and Gruyère until golden and bubbling.
An adjustable mandolin is essential here to achieve slices thin enough to bend and ripple. It’s what creates the signature texture and look of this dish. I’ve linked the mandolin I use and recommend here for anyone wanting to recreate the effect at home.
This gratin is baked in a lidded casserole dish, which is ideal for recipes like this. The depth allows the rippled layers to sit snugly and upright, while the fitted lid helps the gratin cook evenly before finishing uncovered for a beautifully golden top. It’s the perfect size for entertaining and looks great straight from oven to table.
Shop the round casserole dish here
Rippled Sweet Potato Gratin
Ingredients
Ingredients
- 1 Tbsp extra virgin olive oil for greasing your dish
- 1.7 kg sweet potatoes washed (skin on works best)
- 2 × 240 g Philadelphia Light Cooking Cream Cheese
- 1 Tbsp milk
- 5 cloves garlic finely minced
- Pinch freshly grated nutmeg
- Generous salt and freshly cracked black pepper
- 1 Tbsp fresh thyme leaves finely chopped
- 1 cup grated Gruyère cheese
- ⅓ cup finely grated Parmigiano Reggiano or parmesan
- 1 Tbsp fresh chives finely chopped, to garnish
Instructions
- Preheat oven to 180°C fan-forced.
- Slice the sweet potatoes using a mandolin on the thinnest setting (ideally under 1 mm). The slices should be flexible enough to fold and ripple without breaking.
- Generously grease a shallow casserole or baking dish with olive oil.
- Gently fold and wave the sweet potato slices, layering them upright and snugly into the dish. Season well with salt and pepper. Use any remaining olive oil to brush the potato tops.
- In a jug, whisk together the cream cheese and milk until smooth. Stir through the garlic, nutmeg, thyme, and a generous seasoning of salt and pepper.
- Combine the Gruyère and parmesan. Sprinkle a layer over the sweet potatoes, reserving a small handful for the top.
- Pour the cream cheese mixture evenly over the gratin, allowing it to seep down between the layers. Finish with the remaining cheese and a little extra thyme.
- Cover tightly with a lid or foil and bake for 60 minutes, until the sweet potatoes are tender when pierced.
- Uncover and bake for a further 20 minutes, or until deeply golden, bubbling at the edges, and lightly crisp on top.
- Rest for 10 minutes, then finish with chopped chives and serve.
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