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When Life Gives You Onions – Caramelised Onion Tart

Banish the Onion quote 2

You may recall that I was given a huge box of very large onions some weeks ago. I was umming and ahhing what to do with them all. Many readers made suggestions, the most popular being caramelised onions and French onion soup. I had already planned to make a caramelised onion relish (16 onions = 5 small jars) and to slice some to freeze for later use (6 onions = 3 bags). I would have loved to have made a French onion soup but it’s just far too hot at this time of the year to contemplate making soup, let alone eating it. So more onions sliced and frozen for soup making later in the year (6 onions = 2 bags). Anthony requested a Caramelised Onion Tart. Not that I’d ever made one but it obviously appealed to him and coincidentally, I had the same thought. So Caramelised Onion Tart is was (3 onions = 1 tart)

Now to make a tart, you need to have pastry. Pastry and I are not good friends. Nor are pastry and a Brisbane summer. I have mastered to some degree the art of baking however pastry eludes me. I know this will draw comments of ‘Oh it’s simple’ and ‘Practice makes perfect’ but trust me, I do not have the touch. Still, I did my best and I was fairly happy with the result but it took a bit of doing and tongue sticking out so maybe I need to practice some more and finally master the dark art. I still have half a box (36 onions = lots of slicing) to practice with.

Caramelised Onion Tart

Tart caramelised closeup


  • 2 cups plain flour
  • 150g chilled butter, cubed
  • 2 – 3 tbsp water, chilled
  • ¼ tsp salt

Caramelised Onions

  • 3 x brown onions (peeled), halved & finely sliced
  • 2 x tbsp browns sugar
  • 4 – 5 tbsp oil for frying


  • 4 x eggs
  • 1 ½ cups cream
  • ½ cup mature cheddar, grated
  • Few sprigs of thyme
  • Seasoning to taste

Caramelised Onions

  1. Heat oil on a medium heat in a large frying. You want plenty of room so the moisture can evaporate and the onions don’t stew.
  2. Reduce heat slightly, add onions and stir to coat in oil. Cook slowly for 30 minutes to 1hr, stir regularly so onions do not stick. Onions will gradually start to take on a golden colour.
  3. If you continue on a very low heat, you can caramelise the sugars in the onions naturally over the next several hours. Or, once the onions are fully cooked and slightly golden, you can stir brown sugar into the onions to assist in caramelisation.
  4. Stir regularly and do not allow to stick. Add a dribble of water if onions are catching but sugar has not yet caramelised.
  5. When brown and sticky, set aside and allow to cool.

Tart trio


  1. Pulse flour and cold butter in a food processor until it resembles breadcrumbs. You may need to open the lid and scrape down some of the butter.
  2. Slowly add iced water, one tablespoon at a time until a rough dough forms. You may not need all of the water.
  3. Turn dough into a bowl and give a quick, gentle knead to bring together. Cover in plastic wrap and refrigerate for 30 minutes to allow dough to rest and chill.

Filling & Baking

  1. Whilst pastry is chilling, prepare filling by mixing eggs, cream and cheese in a bowl. Add seasoning and leaves from thyme into the mix. Set aside in fridge.
  2. When you are ready to roll out the pastry, pre-heat the oven to 180c
  3. After 30 minutes, gently roll pastry out on a flat surface to a 3mm thickness. If you roll it out on baking parchment, this will assist in lifting it.
  4. When pastry is rolled even, lift into a 25cm greased tart tin or pie dish (baking paper on top). Gently press into dish, taking care to make sure it is pressed lightly into corners.
  5. Cut away excess pastry from edge of dish with a knife. Dock pastry by pressing tines of a fork into the pastry base several times. Also press fork three or four times into corners of dish.
  6. Line pastry with baking paper and fill with baking weight, dried rice or beans. Place in pre-heated oven and blind bake for 10 minutes.
  7. Remove paper and weights from shell and return to oven for 5 minutes to finish cooking and brown slightly.
  8. Remove from oven and allow to cool.

Tart caramelised whole

Final Bake

  1. When pastry and onions are both cool to touch, place onions in base of tart, spreading evenly. Gently pour egg and cream mix over the onions to fill the tart.
  2. Place in 180c oven and reduce immediately to 160c. Bake for 40 – 45 minutes (no fan) until it’s set.
  3. Remove from oven and allow to cool slightly before slicing and serving with a crisp garden salad.
  4. Also good the next day, taken from the fridge and allowed to return to room temperature.

Though I have a tart tin, I chose to make this in a pie plate as I thought the tin was too shallow on this occasion. I also had some excess pastry so I just pressed out the rest into a set of shallow patty cake tins and blind baked them as tartlet shells and popped them into the freezer

Tart caramelised sliced

21 comments… add one
  • Liz Posmyk of Bizzy Lizzy's Good Things January 9, 2015, 11:10 pm

    This looks and sounds delicious, Fiona… a great way to make good use of those onions… and, you’re right, it’s too darned hot for French onion soup, as tasty as that is.

    • Fiona Ryan January 10, 2015, 5:23 pm

      I’m hungering after that soup but I need to be sensible!

  • Jan Rhoades January 10, 2015, 8:26 am

    Yum. Looks delicious. Sorry about the lack of pasty-making-genes! If there are still some onions around tomorrow arvo, I’ll help you peel and slice the last of them.

    • Fiona Ryan January 10, 2015, 5:23 pm

      You’ve outed yourself. Don’t worry, we have the ‘make it up as you along gene’. xx

  • Joanne T Ferguson January 10, 2015, 11:18 am

    G’day I think it looks great Fiona! I wish I could come through the screen and try some now! Well done!
    Cheers! Joanne

    • Fiona Ryan January 10, 2015, 5:26 pm

      All gone now Joanne but Anthony wants me to make it again. Does he not understand the pastry pressure?!

  • sherry from sherryspickings January 10, 2015, 1:27 pm

    i adore this tart. can there be anything more scrumptious than caramelised onion? Oh yes PLUS bacon. 🙂 Yep summer makes it hard to deal with pastry and such like. I often make the maggie beer one in the food processor- so damn simple even i can make it. back at work yet? have a good weekend.
    sherry x

    • Fiona Ryan January 10, 2015, 5:28 pm

      I thought of the Maggie one but no sour cream. I just plunged in confidently if not competently.

  • Nicole - Champagne and Chips January 10, 2015, 2:32 pm

    That is some serious fordporn. It looks magnificent. I’ve only actually succeeded in making caramelised onions once. I always rush and just make stewed onions. This has given me incentive to try again 🙂

    • Fiona Ryan January 10, 2015, 5:28 pm

      Yes, the sugar just makes it so much easier. I don’t take great photos so your food-porn comment has made my day!

  • Tandy | Lavender and Lime January 10, 2015, 3:34 pm

    I seldom make pastry when it’s hot but if I do, I use my marble slab and the fridge to keep it cold enough to work with. Glad you found a use for the onions 🙂

    • Fiona Ryan January 10, 2015, 5:31 pm

      I actually have a marble slab but no room for it in my fridge. It worked OK in the end though.

  • Jan Rhoades January 10, 2015, 4:23 pm

    Yum. Looks delicious. If therre any more onions to peel and chop tomorrow arvo, I’m happy to lend you a hand.

  • Mel @ The cook's notebook January 12, 2015, 1:59 pm

    what a wonderful gift! I read an Indian study years ago that said if you eat brown onion every day it helps lower cholesterol, which is one reason why most Indian curries call for brown onion. I love the look of your tart. Pastry was always a nightmare for me too until I started making it in a food processor. Quick and easy.

    • Fiona Ryan January 14, 2015, 4:06 pm

      Thanks Mel. It’s been incredibly popular on Pinterest so I must have done an alright job with the photo!

  • Jan (A gluttonous wife) January 12, 2015, 7:17 pm

    looks delicious, I think I can smell it 😀 Jan x

    • Fiona Ryan January 14, 2015, 4:09 pm

      Anthony is all set for another this weekend. Maybe I should get him to do the onion bit – that’s what takes the longest! Thanks for stopping by.

  • Maureen | Orgasmic Chef January 12, 2015, 8:55 pm

    You are the onion tart queen! I love this tart and your pastry is wonderful. Did I say I loved it??

    • Fiona Ryan January 14, 2015, 4:10 pm

      Now that’s a title I can accept graciously. Perhaps I should make a little badge for my site : )

  • Wayne Scott January 31, 2015, 10:07 am

    This looks absolutely incredible! I can see this as a perfect meal by the fire. Delicious.

    • Fiona Ryan January 31, 2015, 10:11 am

      Thanks Wayne. It’s been very popular. Don’t rush the onions beacuse that’s what it’s all about!

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