Onion tart

Slow cooked onions give a sweet caramelised taste to this tasty puff pastry tart by Justine Schofield
By Justine Schofield
Onion tart
  • Rating:
  • Serves: 6-8
  • Cook Time: 1 hour 45 minutes
  • Prep Time: 20 minutes
  • Effort: easy


  • 3 large onions, finely sliced
  • 3 sprigs thyme
  • 1 bay leaf
  • 20 g butter
  • 1 tbsp olive oil
  • 2 sheets of puff pastry
  • 25 g butter
  • 2 tbsp flour
  • 190 ml milk
  • 1 egg yolk
  • ½ tsp nutmeg
  • 100 - 150 g gruyère cheese


1. Pre heat the oven to 200C/180C/gas 6. Grease a medium- large tart tin. Line the tin with the pastry and poke all over with a fork. Place a large piece of grease proof paper in the tart shell and chill in the fridge for 10 minutes. Place cooking weights on top of the grease proof paper and bake for 30 minutes.

2. Remove from the oven and place in a dry place. Turn the oven down to 175C/155C fan/gas 5.

3. Melt the butter with the oil in a large pan on low heat. Add the onions, bay leaf and thyme. Season well with salt and pepper and cook on a low heat for 45 minutes. Stir regularly until the onions are soft and translucent. Allow to cool slightly and remove the thyme sprigs and bay leaf.

4. For the béchamel: melt the butter in a small saucepan. Add the flour and stir to make the roux. Gradually add all the milk. Turn the heat up and whisk until the mixture becomes thick. Remove from the heat and season well with the salt and pepper. Add the nutmeg and cheese. Allow to cool slightly before whisking in the egg yolk.

5. Add the béchamel to the onions and allow to cool slightly. Spoon onion mix into the pre-cooked tart shell and bake for 40 minutes or until golden brown and set

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