Step 1

For the pastry, put the flour, salt and butter in a food processor and whizz to fine crumbs (or rub between your fingertips in a bowl if you don’t have a food processor). Beat the egg yolk with 1 tbsp cold water, then gradually add to the flour mixture and whizz (or mix in with a cutlery knife) until the mixture starts to clump together – you may not need all the egg mixture. Bring together into a ball, then flatten into a disc, wrap and chill for at least 30 minutes.

Step 2

Meanwhile, slice ½ of the leeks into 1.5cm-thick rounds. Halve the remaining leek(s) lengthways, then slice into halfmoons. Melt ½ of the butter in a large frying pan, then arrange the leek rounds in a single layer. Cook for 2-3 minutes on each side over a low heat, carefully turning with tongs halfway, until softened and lightly golden. Set aside on a plate.

Step 3

Add the remaining butter to the pan, then gently sauté the half-moon leek slices for 3-5 minutes until softened. Add the baby spinach, cover with a lid (or a baking tray) until wilted, then uncover and bubble off any excess water. Season, stir in the thyme, then tip the veg mixture into a bowl to cool. Once cooled, stir in the mascarpone and mustard until combined. Fold through the cubes of taleggio, then season if needed and set aside.

Step 4

Preheat the oven to 200°C, gas mark Line a large baking tray with a sheet of baking parchment. Lightly flour the work surface, then roll out the pastry to a rough 30cm-diameter circle before carefully transferring it to the lined tray with the help of a rolling pin. Dollop the mascarpone mixture into the centre and spread it out towards the edges, leaving a 6cm border. Arrange the leek rounds snugly on top of the cheese mixture.

Step 5

Fold the pastry edges over the filling, overlapping and pinching the pastry as you fold. Brush the pastry border with the beaten egg, then bake for 20 minutes. Remove the galette from the oven, scatter with the pine nuts and bake for a final 20-25 minutes or until the pastry is deep golden. Remove from the oven and leave to cool before slicing and serving warm (or at room temperature).