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Winter Greens Gratin

This seasonal winter greens gratin is a sophisticated vegetarian side dish that brings a touch of luxury to your table. Featuring a blend of earthy kale and peppery mustard greens, the vegetables are draped in a nutmeg-scented cream sauce and topped with a generous layer of nutty Gruyère cheese. A final coating of crisp, herby Parmesan breadcrumbs provides a wonderful texture contrast to the tender, savoury greens beneath.

Perfect for a Sunday roast or as a centrepiece for a festive dinner, this hearty bake can be assembled in advance to save time on the day. The combination of leafy greens and rich cream makes it a comforting choice for colder months, offering a nutritious yet indulgent way to enjoy seasonal produce. Serve it alongside roasted root vegetables or crusty sourdough bread for a truly satisfying meal.

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Ingredients for Winter Greens Gratin

  • 1 tablespoon unsalted butter plus more for dish

  • 900g kale, centre ribs and stems removed, torn into large pieces, or two 275g bags trimmed, chopped kale (about 24 cups)

  • Kosher salt

  • 1.1kg mustard greens, centre ribs and stems removed, torn into large pieces

  • 60ml extra-virgin olive oil

  • 725ml coarse fresh breadcrumbs

  • 60g finely grated Parmesan

  • 2 teaspoons fresh thyme leaves, divided, plus 7 sprigs thyme

  • 2 shallots, sliced into 1/4"-thick rounds (about 240ml )

  • 240ml double cream

  • 240ml whole milk

  • 7 garlic cloves, smashed

  • 1/8 teaspoons freshly ground nutmeg

  • Freshly ground black pepper

  • 150g coarsely grated Gruyère

Lightly butter a 3-quart baking dish. Working in batches, blanch kale in a pot of boiling lightly salted water until just softened, about 3 minutes. Using a slotted spoon, transfer kale to a large bowl of ice water; let cool, then drain. Squeeze out as much excess water as possible by hand and transfer kale to a work surface.

Repeat with mustard greens, blanching for 2 minutes per batch. Coarsely chop all greens and combine in a large bowl (you should have 6 cups tightly packed greens). Separate clumps and loosen chopped leaves by hand.

Heat oil in a 12" skillet over medium heat. Add breadcrumbs and cook, stirring frequently, until golden and crispy, 8-10 minutes. Transfer to a large bowl; stir in Parmesan and 1 teaspoon thyme leaves. DO AHEAD: Greens and breadcrumbs can be made 2 days ahead. Cover greens and chill. Store breadcrumbs airtight at room temperature.

Melt 1 tablespoon butter in a medium saucepan over medium-high heat. Add shallots; cook, stirring often, until slightly softened and light golden, about 5 minutes. Transfer shallots to bowl with greens. Add cream, milk, garlic, and thyme sprigs to same saucepan; bring to a simmer. Cook until mixture is thickened and reduced to 230g , 10-12 minutes. Discard thyme sprigs and garlic; stir in nutmeg. Season mixture with salt and pepper.

Pour cream mixture over greens in bowl and toss to evenly coat in sauce; season to taste with salt and pepper. Transfer greens mixture to prepared baking dish; sprinkle Gruyère over. Top with breadcrumbs. Cover dish with foil. DO AHEAD: Gratin can be assembled 1 day ahead.

Preheat oven to 204°C. Bake until filling is hot, about 25 minutes. Uncover and bake until cheese is melted, edges are bubbling, and breadcrumbs are golden brown, 10-20 minutes longer. Garnish with remaining 1 teaspoon thyme leaves.

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.

  • 28 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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