• 210 g wholemeal spelt flour, plus extra for dusting
• 100 g butter, cold and cut into cubes
• pinch of salt
• 1 egg yolk
• 1 tbsp sesame seeds
• 1–2 tbsp cold water
• 1 egg white

For the filling

• 1 tbsp light olive oil, plus extra for drizzling
• 1 leek, finely diced
• 2 garlic cloves, finely chopped
• 1 tbsp fresh thyme leaves
• 200 ml double cream
• 220 g crème fraiche
• 4 eggs, lightly beaten
• 50 g freshly grated Parmesan cheese
• 1 courgette, thinly sliced into coins (this is best done on a mandolin)
• sea salt and freshly ground black pepper

Equipment

• food processor
• 25cm loose-bottomed fluted tart tin, about 2.5cm deep
• ceramic baking beans or dried pulses or rice

To make the pastry, put the flour and butter in a food processor with the salt and blitz together until the mixture resembles breadcrumbs. Then add the egg yolk and pulse again until the dough starts to come together. Add the sesame seeds, and pulse, adding just enough water so that the mixture comes together to make a soft but not sticky dough, with no dry bits.

Tip the dough onto the work surface and bring it together to form a ball. Wrap the ball in cling film, squish it down a bit and then pop it into the fridge for 30 minutes, so that the mixture of proteins (gluten) in the dough can relax. This helps to ensure that the pastry will not shrink when it is cooked.

After 30 minutes, sprinkle a little flour on the work surface and roll out the pastry to the thickness of half a £1 coin (about 1.5mm). Then put the rolling pin across the centre of the dough and fold half of the dough over the rolling pin. Lift the rolling pin and dough up and place it over the tart tin. Carefully ease the pastry into the tart tin. Be really careful not to stretch or pull the pastry in any way, because if you do the pastry might shrink while it is cooked.

I like to use a little ball of pastry rolled up and dipped into flour to ease the pastry into the ‘corners’ of the tin. Take a sharp knife and trim off the excess, and then take a wooden spoon and use this to very, very gently press the pastry into the ‘flutes’ of the tin. Pop the tin into the fridge for 10 minutes to allow the pastry to rest for a second time.

Preheat the oven to 180°C (fan 160°C/350°F/gas 4). Cut a sheet of baking parchment into a circle, about 35cm in diameter. Scrunch it up so that it will sit in the tin, then open it up and use it to line the pastry. Fill the tin with ceramic baking beans, dried pulses or rice, making sure that they go right up to the sides of the tin. Place the tin on a baking sheet (this makes it easier to move the tin around) and place it in the oven.

Bake the tart for 15–20 minutes, until the pastry looks like it is just beginning to set but is not coloured. Remove the tart from the oven.

Carefully draw up the edges of the parchment to remove it from the pastry and discard. Brush the base with the egg white to help to seal it and avoid a soggy bottom and then return to the oven for 5–7 minutes, or until the base feels sandy to the touch and the sides are turning a light golden brown. Once the pastry is baked, remove it from the oven and set aside. Turn the oven down to 150°C (fan 130°C/300°F/gas 2).

While the pastry is baking, prepare the filling. Heat the oil in a frying pan over a medium heat and cook the leek for 8–10 minutes, until softened but not coloured, stirring occasionally. Add the garlic and the thyme and cook for another minute, then tip this into a large jug. Add the double cream, crème fraiche, eggs and Parmesan and beat together to just combine. Season with salt and pepper.

Carefully pour the egg mixture into the cooked pastry case and then arrange a layer of the sliced courgette on top. Season the courgette slices lightly with salt and pepper and then drizzle them with a little olive oil. Return the tart to the oven and cook for another 30–40 minutes, or until the tart is cooked through but still wobbles very slightly in the centre. Remove the tart from the oven and leave to cool for a few minutes before cutting into slices to serve. This is delicious served both hot and cold.