Sliced caramelised onion and cheese puff pastry tart

Caramelised onion puff pastry tart

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(6 ratings)

Prep: 10 mins Cook: 50 mins


Serves 4 - 6

Top puff pastry with tangy mustard, onions and Parmesan cheese for a light vegetarian lunch or party buffet nibble

Nutrition and extra info

  • Vegetarian

Nutrition: per serving (6)

  • kcal380
  • fat22g
  • saturates8g
  • carbs35g
  • sugars9g
  • fibre3g
  • protein9g
  • salt1.2g
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  • 850g large onions



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

  • 3 tbsp olive oil, plus extra for greasing
    olive oil

    Olive oil

    ol-iv oyl

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

  • 320g pack ready-rolled all-butter puff pastry
  • 1 egg, beaten



    The ultimate convenience food, eggs are powerhouses of nutrition packed with protein and a…

  • 2 tbsp Dijon mustard
  • 25g fine breadcrumbs
  • 50g grated parmesan (or vegetarian alternative)



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

  • ½ tsp thyme leaves


  1. Finely slice the onions, then put them in a large, lidded pan with the oil and cook over a low heat for 30 mins, stirring from time to time.

  2. Remove the lid and turn up the heat, cooking the onions until they brown and caramelise, stirring often.

  3. Heat oven to 180C/160C fan/gas 4. Unroll the pastry and place on a greased baking sheet. Using a sharp knife, cut a 2cm border around the edge of the pastry, going almost but not quite through the pastry. Glaze the edge of the pastry with beaten egg.

  4. Spread the mustard over the base of the tart and pile on the onions, spreading them out to meet the edge. Mix the breadcrumbs, Parmesan and thyme leaves together, and sprinkle this topping evenly over the onions. Bake the tart for 18-20 mins or until the pastry is golden brown.

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Comments, questions and tips

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17th Jan, 2017
This tart was popular with my family. Mine didn't have a soggy bottom but it did stick a little to the metal tray I cooked it on. I used extra Parmesan as my family like cheese. It was very nice cold for lunch the following day.
Minoo's picture
17th Feb, 2016
We liked this tart but would put less mustard in it next time as it was quite overpowering. A simple, cheap dinner that was a hit in our house.
Frantic Flapjack
28th Apr, 2015
At 180c/160c, the oven temperature wasn't hot enough for puff pastry so when my tart came out, it had a very soggy bottom. I turned the temperature up to 200c fan and popped it back in for 10 minutes. The pastry was then cooked through. If I made again, I would put the egg wash all over the pastry, prick the base and bake for 10 minutes before topping it with the onion mixture. The end result was very tasty.
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