Skip to main content

Roasted Onions with Gruyère Croutons

This roasted onions with Gruyère croutons recipe is a celebration of the humble allium, combining seven different varieties for a complex, mellow sweetness. This vegetarian side dish transforms red and white pearl onions, shallots, and spring onions into a sophisticated centrepiece. The vegetables are slow-roasted until caramelised and tender, providing a savoury base that pairs beautifully with the rich, nutty notes of the melted Swiss cheese.

Ideal for a Sunday roast or a festive dinner party, this comforting bake features rustic, shop-bought bread torn into chunky croutons that soak up the flavourful stock. Because the onions can be roasted a day in advance, it is an excellent choice for stress-free entertaining. Serve it alongside roasted meats or as a substantial vegetarian main with a crisp green salad to balance the richness.

Continue reading below

Ingredients for Roasted Onions with Gruyère Croutons

  • 12 white pearl onions, peeled

  • 12 red pearl onions, peeled

  • 8 large shallots, peeled, halved through root end

  • 6 large spring onions, dark green tops trimmed

  • 2 medium sweet onions (such as Vidalia), peeled, cut into 3/4-to 1-inch wedges through root end

  • 1 large red onion, peeled, cut into 3/4-to 1-inch wedges through root end

  • 1 brown-skinned onion, peeled, cut into 3/4-to 1-inch wedges through root end

  • 3 tablespoons extra-virgin olive oil

  • 1 tablespoon fresh thyme leaves

  • 1 teaspoon coarse kosher salt

  • 1/2 teaspoons freshly ground black pepper

  • 725ml coarsely torn 1/2-inch pieces rustic bread with crust

  • 240ml low-salt chicken broth

  • 170g Gruyère cheese, coarsely grated (about 230g packed)

  • Sea salt flakes or crystals

How to make Roasted Onions with Gruyère Croutons

Preheat oven to 232°C. Combine all onions and shallots in large bowl. Drizzle evenly with olive oil, then sprinkle with thyme, coarse salt, and pepper; toss gently to coat. Spread out in single layer on large rimmed baking sheet.

Roast onions until tender and beginning to brown in spots, 25 to 30 minutes. Scatter bread pieces on another rimmed baking sheet. Bake bread until golden brown, 7 to 8 minutes. Cool bread on baking sheet. Arrange onions in single layer in large casserole dish. DO AHEAD: Onions and croutons can be made up to 1 day ahead. Cover onions and refrigerate.

Store croutons in airtight container at room temperature. Bring onions to room temperature before continuing.

Preheat oven to 204°C. Spoon broth over onions to moisten. Scatter croutons over; sprinkle with cheese. Bake until heated through and cheese is melted, about 20 minutes. Sprinkle with sea salt flakes and serve.

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
flu eligibility checker

Ask, share, connect.

Browse discussions, ask questions, and share experiences across hundreds of health topics.

symptom checker

Feeling unwell?

Assess your symptoms online for free

Sign up to the Patient newsletter

Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.

Please enter a valid email address

By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.