Because of using 28 cm tart dish for the recipe of 24 cm, our tart was slightly thiner but the taste is amazing and recipe is quite practical:
For the filling:
285ml buttermilk (one standard supermarket tub)
100ml double cream
15 bay leaves
50g melted unsalted butter
180g caster sugar
2 tbsp plain flour
½ tsp grated lemon zest
For the pastry:
150g plain flour
¼ tsp salt
80g cold unsalted butter, cubed
35ml ice-cold water
First make the pastry. Mix the flour and salt in a large bowl, then add the butter and, with your hands, rub in until it resembles breadcrumbs. Stir in the water and bring the mixture together to form a dough. Stop mixing as soon as it comes together, wrap in clingfilm and store in the fridge for at least two hours.
Meanwhile, put the buttermilk, cream and bay leaves in a medium saucepan. Place on a very low heat and simmer for about 10 minutes, stirring all the time, making sure the buttermilk does not boil and split. If you have a thermometer, use it to check that the milk is not going above 70C. Leave to cool for at least an hour (or overnight, if you have time), then remove the bay leaves and stir in the melted butter.
Heat the oven to 170C/335F/gas mark 3. Roll out the pastry into a 32cm-diameter circle. Very lightly grease a fluted tart tin that’s 24cm in diameter with a 4cm edge, and line with the pastry. Chill for 30 minutes, then line with parchment paper, fill with baking beans and bake for 25 minutes. Remove the beans and paper, bake for another 10 minutes until golden, then set aside to cool.
Raise the oven temperature to 180C/350F/gas mark 4. Whisk together the eggs and sugar until light and airy. Fold in the infused buttermilk, followed by the flour and lemon zest, and mix gently until smooth. Pour into the pastry shell and cook for 30 to 35 minutes, until just set. Remove from the oven and leave to cool down. Take out of the tin and serve at room temperature.