Recipe of the week: Petersham Nurseries' pear and walnut upside-down tart

Taken from Petersham Nurseries, by the Boglione Family (Petersham Nurseries, £65)

Many people shy away from making caramel, but there’s really nothing to fear. The trick is in knowing when to stir – and when not to.

Serves 8

For the rough-puff pastry

• 250g plain flour
• 250g unsalted butter, firm but not chilled (remove from the fridge 2 hours before use)
• 1tsp salt
• 125ml iced water

###For the tart

• 150g caster sugar
• 100g unsalted butter, cubed
• 3 ripe pears, peeled and cored and cut in half vertically
• 1 large egg white
• A handful of walnuts, toasted
• 200ml crème fraîche, to serve

First make the pastry. Pour the flour into a large bowl and make a well in the middle. Dice the butter and add to the centre of the well with the salt.

Gradually mix the ingredients together with your fingertips. When the cubes of butter have become very small and the mixture resembles rubble (you should still be able to see some small chunks of butter), add a little of the iced water and mix together. Continue adding the water slowly until you have a firm dough (you may not need all the water). Mix until combined, but do not be tempted to knead.

Place the dough onto a lightly floured surface and roll into a 30 cm x 30cm square. Fold into thirds, as if folding a letter, to make three layers. Turn vertically through 180°, roll to flatten and then fold again. Turn again through 180° and repeat. Chill the pastry for 20 minutes, then roll and fold the pastry twice more as above. Keep in the fridge until needed.

Preheat the oven to 180°C.

To make the caramel, place the sugar in a heavy-bottomed, oven-safe 28cm frying pan and cook over a medium-low heat, not stirring, for around 10 minutes, or until it has melted and starts to bubble (you may find it helpful to gently swirl the pan once or twice towards the end).

Remove from the heat and carefully add the butter, whisking constantly until combined. If it splits, put it back over a low heat and whisk continuously until it comes together. Arrange the pears, core side up, in a circle around the pan.

Roll out the pastry into a circle large enough to cover the pears and place gently over the top, pushing down the pastry around the sides. Make a hole in the middle and brush with the egg white. Bake for 30-40 minutes until golden brown, then remove from the oven and allow to cool for at least 10 minutes, as the caramel will be piping hot and can easily burn.

To remove the tart from the pan, place a large plate on top of the pan, then with both hands squeeze the plate and pan together and flip over. This moves the pastry to the bottom and reveals the pears, now beautifully caramelised. Sprinkle with the walnuts and serve with the crème fraîche.

Photography by Andrew Montgomery