Creamy potato gratin with caramelised onions

Creamy potato gratin with caramelised onions

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(8 ratings)

Prep: 20 mins Cook: 2 hrs, 15 mins


Serves 8
The sweetness of the caramelised onions cuts through the rich creaminess of this dauphinoise-style bake

Nutrition and extra info

  • Freezable

Nutrition: per serving

  • kcal357
  • fat23g
  • saturates12g
  • carbs31g
  • sugars4g
  • fibre3g
  • protein9g
  • salt0.29g


  • 2 tbsp olive oil
    olive oil

    Olive oil

    ol-iv oyl

    Probably the most widely-used oil in cooking, olive oil is pressed from fresh olives. It's…

  • 2 onions, thinly sliced



    Onions are endlessly versatile and an essential ingredient in countless recipes. Native to Asia…

  • 2 thyme sprigs, leaves picked, plus extra to serve


    This popular herb grows in Europe, especially the Mediterranean, and is a member of the mint…

  • 150ml double cream
  • 175ml milk



    One of the most widely used ingredients, milk is often referred to as a 'complete' food…

  • 1¼kg/2lb 12oz large potatoes, peeled and thinly sliced



    The world's favourite root vegetable, the potato comes in innumerable varieties. A member of…

  • butter, for greasing



    Butter is a dairy product made from separating whole milk or cream into fat and…

  • 100g crème fraîche
  • 85g parmesan, grated



    Parmesan is a straw-coloured hard cheese with a natural yellow rind and rich, fruity flavour. It…


  1. Up to 2 days before serving, heat oven to 200C/180C fan/gas 6. Heat the oil in a large frying pan. Add the onions and thyme, cover, and cook over a gentle heat for 10-15 mins until softened and caramelised. Pour the cream and milk into a large bowl and season well. Add the potatoes and mix to combine.

  2. Butter a 23 x 28cm ovenproof dish, then layer in half the potatoes. Spread the onion mixture on top, then layer on the remaining potatoes. Press down with your hands. Pour over the milk mixture, which should come just level with the potatoes. If not, add a little more milk until it does. Cover with foil, then bake for 11⁄2 hrs until tender. Remove from the oven and leave to cool. Cover and store in the fridge.

  3. On the day, heat the oven to 220C/200C fan/gas 7. Uncover the gratin, spread the crème fraîche on top, then sprinkle over the Parmesan. Put in the oven and cook for 30 mins until the cheese is melted, the top crisp and golden brown, and the gratin piping hot. Serve garnished with extra thyme.

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Comments, questions and tips

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Nervous nellie
28th Jan, 2019
My cousin Toni made this dish for me as she knows I love potato gratin. It was unbelievable. A dish I won’t forget in a long time. Delicious!
5th Jul, 2015
This went down a treat in my house. I will certainly be cooking it again.
13th Feb, 2015
Does anyone know is the weight of 11/4kg potatoes before being peeled or after?
21st May, 2013
Just used this for caramelised onions and thought a tsp of sugar would have been a good addition to the recipe...
27th Apr, 2013
Absolutely delicious. A big hit with my dinner guests. Easy to prepare.
2nd Nov, 2012
I made this last Christmas and I'm really glad to have run across the recipe again so I can make it this year. We served roast rib of beef and the creamy potatoes and onions went perfectly with it. I made this dish the day before and it was gorgeous.
20th Sep, 2012
Absolutely gorgeous! Highly recommended - eo easy, yet soooo tasty!
21st Feb, 2012
Yum,yum,yum. This is delicious and creamy. Have made this recipe several times and it comes out perfect every time. The addition of the caramelised onions takes it to another level. I urge anyone to try it - you won't be disappointed.
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