Roasted Onions

Roasted Onions

5 from 8 reviews

With just five simple pantry ingredients and two fresh herbs these easy sweet caramelized Roasted Onions make the most aromatic and flavorful side dish.


  • 4 medium sweet onions sliced in half from root to tip
  • 3 tablespoons olive oil
  • 2 tablespoons butter
  • kosher salt
  • fresh ground black pepper
  • fresh rosemary, chopped
  • fresh thyme leaves


  1. Preheat the oven to 400 degrees.  Cover a small baking sheet with parchment paper.
  2. Cut the onions in half from tip to root then remove the outer dried layers. Lay them cut side up on the prepared baking sheet.
  3. Drizzle with olive oil and top each half with a pat of butter. Sprinkle generously with kosher salt and fresh ground black pepper. Top with fresh thyme leaves and chopped fresh rosemary.
  4. Roast 40-45 minutes or until golden brown and tender.  Sprinkle with more fresh thyme and rosemary. For best results serve promptly.


  • Use sweet yellow onions or Vidalia onions. Slice the onions in half vertically from tip to root.
  • Any number of fresh herbs will work with this recipe. We love using thyme, rosemary, Italian parsley, or whole cloves of garlic added to the baking sheet.
  • Try dried herbs like oregano or sage. I find these herbs are better used dried as they complement the onions better and are not bitter like their fresh counterparts.
  • Parchment paper helps the onions brown better and cook more evenly. It is usually rated up to 420 degrees Fahrenheit as long as you keep it away from any open flames. As an added bonus it makes for easy clean up.
  • These sweet treats are best served promptly but they can easily be heated again in the hot oven for about 5 minutes.
  • Store leftovers in an airtight container in the refrigerator for up to 3 days. 

Keywords: how to roast onions, how long to roast onion, oven roasted onions

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