Mushroom and Onion Tart

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A simple-to-construct freeform tart made with ready-rolled pastry – no baking tins needed. The pastry cuddles a filling of chunky chestnut mushrooms, caramelised onions and tarragon with OGGS Aquafaba helping to hold them all together. We think it’s the ideal tart to rustle up for a filling supper, or weekend lunch.

PREP TIME 30 minutes
COOK TIME 55 minutes


  • 1 x 320g vegan ready-rolled puff pastry sheet
  • 2 tbsp olive oil
  • 500g red onions, halved lengthways, peeled, sliced into thin wedges
  • 200g chestnut mushrooms, cut into chunky slices, halved if small
  • Generous grinding of black pepper
  • 75g dairy-free cream cheese
  • 11/2 tsp Dijon mustard
  • 1/4 tsp sea salt, plus a pinch
  • 2 tbsp self-raising flour
  • 1/4 tsp baking powder
  • 4 tbsp dairy-free milk
  • 1 tbsp chopped tarragon leaves
  • 100ml OGGS Aquafaba
  • 30g your favourite vegan cheese, grated
  • handful of pea shoots or rocket to finish it off


  1. Take the pastry sheet out of the fridge – it will be easier to unroll later. Line a large baking tray with baking parchment.
  2. Heat the oil in a large frying or sauté pan. Fry your onion wedges with a pinch of salt on a medium heat, about 20 minutes. Stir them every now and then – not all the time, as you want them to catch and char on the bottom of the pan to give flavour.
  3. When the onions are softened and looking caramelised, preheat the oven to 200°C/180°C if using a fan oven/gas mark 6. Raise the heat under the onions slightly, tip in the mushrooms and fry for another 3-4 minutes to brown them, stirring occasionally. Season with pepper, remove the pan from the heat and then leave the veg to cool so they aren’t too hot when they go on the pastry.
  4. Now get on with the rest of the filling. Mash the vegan cream cheese in a medium bowl with the back of a fork, then mix in the mustard, 1/4 tsp salt, some pepper, the flour and baking powder, followed by the milk and tarragon, to make a thick paste. Pour the OGGS Aquafaba into a large bowl and whisk using an electric hand whisk for 3 minutes until it is light and frothy and reaches soft peaks. Tip the cream cheese mixture into this, and gently fold together with a rubber spatula to give a thickish but light and airy mix.
  5. Your veg and filling are done – so you can get on with shaping the tart. Unroll the pastry sheet and lay it on the lined baking sheet. To make a border to contain the filling, work on one side of the pastry at a time and brush the edge of it with cold water. Fold it over to a 2cm width, and press the edge down onto the pastry base to secure. Bring the fold upright to create a border. Repeat with the remaining 3 sides, making sure you have a sturdy border all round.
  6. Spoon and spread half the onion and mushrooms evenly over the pastry base, keeping them inside the pastry border. Check the sides of your tart are still standing up, so the filling can’t escape. Stir your frothy Aquafaba filling then carefully pour it over the veg so it evenly covers them (transfer to a jug first if that’s easier to pour from). Scatter over the rest of the veg, keeping it all nice and loose – then sprinkle over the grated cheese.
  7. Time to get the tart baked - so pop it in the oven on the middle shelf for 30minutes until the filling is slightly puffy and set, and the pastry golden. You may not be able to wait – but try and let it sit for 10 minutes before serving, so it can all settle down. To serve, finish it off with a light scattering of pea shoots or rocket, and eat freshly baked.

Top Tips

  • Experiment with your own mix of mushrooms to include some exotic ones, like shiitake, or oyster (which are extra-meaty).
  • Fancy adding a dash of heat? Stir a few dried chilli flakes, about 1/4 tsp should be enough. But start with a pinch and add more later if you want to check the strength of your chilli flakes

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