3 tbsp olive oil, plus extra for greasing
3 large red onions, thinly sliced
150g chestnut mushrooms, sliced
Salt and black pepper
1 x 320g sheet of ready-rolled puff pastry
1 egg, beaten
2 tbsp Dijon mustard
25g fine breadcrumbs
50g Parmesan (or vegetarian alternative), grated
½ tsp fresh thyme leaves, plus extra to serve
- Heat the olive oil in a deep frying pan over a low heat. Add the sliced onions, cover with a lid and cook for 30 minutes, stirring occasionally.
- Remove the lid and turn the heat to medium. Cook the onions for 10-15 minutes longer until browned and caramelised, stirring often.
- Remove the onions from the pan and set aside. Add the sliced mushrooms to the pan and cook over a medium heat for 4-5 minutes until softened and beginning to brown. Season with salt and pepper. Remove from the heat and set aside.
- Preheat the oven to 180 ̊C/160 ̊C fan/gas mark 4. Line a large baking tray with non-stick parchment paper.
- Unroll the pastry and place on the prepared baking tray.
- Use a sharp knife to cut a 2cm border around the edge of the pastry, being careful not to cut completely through. Brush the edge of the pastry with beaten egg.
- Spread the mustard over the base of the tart. Scatter the mushrooms and caramelised onions over top.
- In a bowl, stir together the breadcrumbs, Parmesan and thyme leaves. Sprinkle the mixture over the tart.
- Bake for 18-20 minutes or until the pastry is golden brown. Sprinkle the tart with some extra fresh thyme and cracked black pepper, then slice and serve with some mixed leaves.
480kcals, 33.9g fat (8.5g saturated), 35.3g carbs (5.9g sugars), 11.8g protein, 3.9g fibre, 0.351g sodium