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Poblano Potato Gratin

This vibrant poblano potato gratin offers a sophisticated twist on the classic French side dish. By incorporating charred poblano chillies and sweet sautéed onions, known traditionally as rajas, this vegetarian bake achieves a wonderful depth of smoky flavour that cuts through the richness of the double cream. The Yukon Gold potatoes provide a buttery texture that holds its shape beautifully while soaking up the savoury, mildly spiced sauce.

Ideal for a festive gathering or a comforting weekend meal, this hearty potato dish pairs exceptionally well with roasted vegetables or a crisp green salad. The preparation involves a genuine touch of craft, from blistering the fresh chillies to precision-slicing the potatoes, resulting in a homemade gratin that is as visually impressive as it is delicious.

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Ingredients for Poblano Potato Gratin

  • 675g fresh poblano chillies (about 5)

  • 450g onions, cut lengthwise into 1/4-inch strips

  • 1 tablespoon vegetable oil

  • 1.4kg large Yukon Gold potatoes

  • 350ml double cream

  • 180ml whole milk

  • Equipment: an adjustable-blade slicer

How to make Poblano Potato Gratin

Roast chillies on their sides on racks of gas burners on high, turning with tongs, until skins are blackened all over, about 10 minutes. Immediately transfer to a bowl and let stand, covered tightly, 10 minutes.

When chillies are cool enough to handle, peel or rub off skin. Slit chillies lengthwise, then stem, seed, and devein. Cut lengthwise into thin strips.

Cook onions with 1 teaspoon salt in oil in a 12-inch heavy skillet over medium-low heat, stirring occasionally, until golden, about 8 minutes. Stir in chillies and remove rajas from heat. Reserve 60g rajas for topping.

Preheat oven to 204°C with rack in middle. Generously butter a 3-quart shallow baking dish.

Peel potatoes, then cut crosswise into 1/16-inch-thick slices with slicer. Transfer to a small heavy pot. Add cream, milk, and 1 teaspoon salt and bring just to a boil over medium heat, stirring occasionally (liquid will thicken). Stir in rajas, then pour mixture evenly into baking dish. Sprinkle reserved 120ml rajas on top.

Bake until potatoes are tender, 45 minutes to 1 hour. Let stand 15 minutes before serving.

Disclaimer

While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

Article history

The information on this page is peer reviewed by qualified clinicians.

  • 16 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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