Cornish Three-Cheese & Caramelised Onion Tart Recipe

There are many ways to enjoy great Cornish produce, but this tart gives you the flexibility to make it your own and enjoy local produce.

British and Irish food expert Elaine Lemm is a trained chef and prominent food writer. She has established her own international cookery school and also opened her own restaurant in 1999. Here, she gives us her recipe for a delicious but simple tart that uses local Cornish produce - perfect for a Cornish picnic.

How to make Cornish three-cheese & caramelised onion tart

Cornish three-cheese and caramelised onion tart

On the tart, there are three different Cornish cheeses: Cornish Brie, soft and melting; a Cornish Cheddar to add flavour and texture, and a Cornish Blue to give an added salty bite.

You can change the cheeses to suit your taste, and add your favourite herbs, or even a little spiciness to the tart along with your favourite herbs, even a little spiciness.

Serves 4 as a main course


  • 55g butter
  • 2 tbsp vegetable oil
  • 600g red onions, skinned, halved and thinly sliced
  • 100ml dry white wine
  • 1 tsp fresh thyme leaves
  • A squeeze of Balsamic glaze (optional)
  • 350g puff pastry
  • A little flour for rolling
  • 8 small plum tomatoes
  • Salt and black pepper
  • 3 Cornish cheeses of your choice (see above), at least 2 large tablespoons of each


  1. Heat the butter and oil in a large, roomy, frying pan. Add the onions, cover with a lid and cook gently for 10 minutes. The onions should be soft and translucent

  2. Turn the heat up slightly, add the wine and bubble until the liquid disappears. Add the thyme and the Balsamic glaze, stir then put the onions to one side to cool completely

  3. Meanwhile, lightly dust the worktop with flour and roll the pastry to a rectangle 34cm x 24cm. Lay the rectangle on to a sheet of baking paper

  4. Using a sharp knife, lightly score a 4cm border around the perimeter taking care not to cut all the way through. Pop the pastry into a fridge to rest for 15 minutes

  5. Meanwhile, prepare the cheese. Grate the Cheddar, slice the Brie into tiny pieces, and crumble or cube the blue cheese, or similarly with the cheeses you have chosen; a variety of methods is best

  6. Preheat the oven to 190°C/375°F/Gas 5

  7. Place the pastry on its paper on a baking sheet. Spread the onions carefully within the border. Push the tomato halves into the onions. Scatter your chosen cheeses evenly over the tart and finally, season with salt and pepper

  8. Bake in the preheated oven on a middle shelf for 40 minutes or until the pastry is crisp, risen and golden brown

  9. Serve hot with Cornish new potatoes and a green salad. The tart is also delicious cold for picnics, in a lunch box, or simply as a tasty snack

Check out our 5 favourite local Cornish producers to help you decide where you can get your ingredients from for this delicious recipe! 

If you love the Cornish three cheese and caramelised onion tart recipe, visit cornwall and get the full Cornish experience. Book your stay in our Cornish holiday cottages, where you are that one step closer to the delicious Cornish food.

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