Rosti-filled onions

A must for onion lovers, perfect as an accompaniment or the main dish

  • Prep:15 mins
    Cook:1 hrs 20 mins
  • Easy

Nutrition per serving

  • kcal 344
  • fat 21g
  • saturates 8g
  • carbs 31g
  • sugars 0g
  • fibre 5g
  • protein 10g
  • salt 1.03g


  • 4 large onions, sliced into quarters, keeping root intact
  • 2 tbsp olive oil
  • 2 large potatoes, grated
  • 3 tbsp wholegrain mustard
  • 25g butter
  • 75g vegetarian Gruyère -style cheese, grated
  • 2 large carrots, grated


  1. Heat oven to 200C/fan180C/gas 6. Place the onions on a baking tray, brush with olive oil, season, then cook for about 1 hr until golden and tender.

  2. Meanwhile, mix the potato and carrot together, then stir in the mustard and seasoning. Divide the mixture between the onions, then dot the top of each one with a little butter.

  3. Return the onions to the oven and cook for 15 mins until they are meltingly tender. Sprinkle with the cheese, then cook for a further 5 mins until the topping is golden and bubbling.

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