Side Dish Vegetarian Baking

Two-Tone Scalloped Potatoes

(potato & sweet potato gratin)

By Ido

· April 2026 ·

These two-tone scalloped potatoes layer thinly sliced regular and sweet potatoes in a spiral, poured over with a creamy parmesan sauce and baked until golden and deeply caramelised. It looks far more impressive than it is difficult. The two potatoes balance each other perfectly: sweet potato brings natural sweetness and vibrant colour, regular potato brings the creamy, starchy body of a classic gratin dauphinois. One pan, one sauce, one oven.

Prep

min

Bake

min

Serves

portions

Level

Beginner

Jump to Recipe

Two-tone scalloped potatoes baked golden in a round dish on a wooden board, overhead view

Two-tone scalloped potatoes — golden, caramelised, impossibly easy to make

Why These Two-Tone Scalloped Potatoes Work So Well

Most scalloped potatoes are a single colour and a bit one-dimensional in flavour. Alternating sweet potato and regular potato changes everything. The sweet potato adds natural sweetness and a deep orange colour that makes the spiral look almost too good to eat, while the regular potato keeps the gratin creamy, starchy, and satisfying in the way a classic scalloped potato dish should be.

The sauce is simple but exactly right: cooking cream, milk, butter, and parmesan heated together slowly until the cheese melts in. It gets poured over the arranged potatoes and the dish goes into the oven covered for the first 30 minutes — which steams the scalloped potatoes through and lets them absorb the sauce. The foil comes off for the last 15 minutes under the grill, and that is where the magic happens.

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Key Tool

A mandoline slicer makes these scalloped potatoes look stunning. Even, thin slices of the same thickness mean everything cooks at the same rate and the spiral sits neatly. A sharp knife works too — aim for 2–3 mm.

Two-tone scalloped potatoes ingredients laid out with labels: sweet potatoes, regular potatoes, cream, butter, parmesan and milk — Everything you need for these two-tone scalloped potatoes — simple ingredients, stunning result

How to Make Two-Tone Scalloped Potatoes, Step by Step

Make the cream sauce

In a saucepan over low heat, combine the cooking cream, milk, butter, salt, and pepper. Heat slowly while stirring — just barely bubble, not boil hard or it will scorch.
Once hot, add the grated parmesan and stir until fully melted and smooth. Remove from heat and set aside.

Slice the potatoes

Peel all the potatoes and sweet potatoes. Using a mandoline on medium setting, slice them thinly directly into a large bowl filled with cold water. The water prevents browning while you work.
Try to keep the slices from both types roughly the same size — it makes the spiral neater and ensures even cooking.

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Low and Slow

The cream sauce only needs gentle heat. If it boils too aggressively the cream can split. Keep the flame low and stir often — it comes together in just a few minutes.

Arrange the spiral

Line a round baking pan with parchment paper. Drain the potato slices well.
Alternate one slice of regular potato and one slice of sweet potato into a long row on the counter (white, orange, white, orange).
Take that row and arrange it in a spiral starting from the outer edge of the pan, working inward. This is a great moment to call in the kids.

Raw two-tone scalloped potatoes arranged in a spiral in a round parchment-lined pan, alternating orange and white slices — The raw spiral — build the alternating row on the counter first, then curl it into the pan

Add the sauce and bake covered

Pour the cream sauce over the arranged scalloped potatoes until it almost reaches the tops of the slices. If it doesn't quite cover, add a small splash of water — but don't drown them.
Cover tightly with aluminium foil and bake at 180°C (350°F) for 30 minutes. The potatoes will steam through and absorb the sauce as they cook.

Grill until golden

After 30 minutes, remove the foil. Scatter the shredded mozzarella over the top.
Switch the oven to the grill setting and return for another 15 minutes, or until the top is deeply golden and caramelised.
Keep an eye on it in the last few minutes — cheese can go from perfect to burnt quickly under a grill.
Let it rest for 5 to 10 minutes before serving. It firms up and is much easier to slice neatly.

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Rest Before Serving

Let the scalloped potatoes sit for 5 to 10 minutes after the oven. They firm up slightly as they rest and slice much more cleanly.

Tips for the Best Scalloped Potatoes

🔪 Use a mandoline: Even thickness is everything. Uneven slices mean some scalloped potatoes will be underdone while others overcook. A mandoline gets you consistent, thin slices in a fraction of the time.
💧 Keep slices in water: Once sliced, keep both potato and sweet potato submerged in cold water until you are ready to arrange them. This stops oxidation and browning.
🌀 Build the row first: Lay out your alternating row on the counter before transferring it to the pan. Much easier to get the pattern right when you can see the full row before curling it into a spiral.
🧀 Cheese variations: Parmesan in the sauce adds depth and saltiness. Mozzarella on top gives the golden pull. You can mix in gruyère or cheddar for a stronger, more robust flavour.
🫙 Make ahead: These scalloped potatoes reheat beautifully. Make the day before, refrigerate, and reheat covered in foil at 160°C for 20 minutes. Remove the foil for the last 5 minutes to re-crisp the top.
🥗 Serving ideas: Works as a show-stopping side at a dinner party or a weeknight dish with a simple green salad. Pairs very well with roast chicken or grilled fish.

Frequently Asked Questions About Scalloped Potatoes

Yes. A rectangular dish works fine. Instead of a spiral, arrange the alternating slices in straight overlapping rows like roof tiles. It will look different but still striking. Make sure the dish is deep enough to hold the sauce without it overflowing as the scalloped potatoes cook down.

A sharp knife works if that is all you have. Aim for slices of roughly the same thickness, around 2 to 3 mm. Too thick and the potatoes will be underdone in the centre; too thin and they fall apart when you try to arrange them. A mandoline just makes the job faster and more consistent.

Yes. The sauce thickens significantly as it bakes because the starch from the scalloped potatoes releases into it. It will look liquid when you pour it over the raw slices, but after 30 minutes covered in the oven it will have reduced into a creamy, silky consistency. Do not add flour or extra cream.

Yes. Use full-fat coconut cream or an oat-based cooking cream, plant-based milk, and dairy-free butter. Replace the parmesan with nutritional yeast for a similar savoury depth, and use a dairy-free melting cheese on top. The flavour will be slightly different but the dish still works very well.

Slice directly into a bowl of cold water as you go. The water stops oxidation and keeps both the regular and sweet potato slices looking fresh. Drain briefly before arranging — you do not want excess water diluting the cream sauce.

Drop a comment below and let me know how the spiral turned out. Did you go full cheese on top? If you enjoyed this, the puff pastry meatloaf is another dish that looks far more impressive than the effort it takes. Tag your photos and show off that golden top.

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