1: Make the pastry. Cream together the butter and sugar in a stand mixer with the beater attachment. When smooth, reduce the speed and slowly add the flour and start to bring to a paste. Just before it comes together completely, add the egg. When it has just come together into a paste, remove from the bowl and wrap in cling film. Refrigerate for at least 1 hour, or overnight.
2: Roll out the pastry on a lightly floured surface to the thickness of a £1 coin. Place over baking tin, pushing the pastry in tightly. Let the excess hang over the sides. Line with several layers of cling film or baking parchment and fill with baking beans or uncooked rice or pulses. Place on a baking sheet and cook for 20–25 minutes, until the pastry looks crisp and golden. Remove the beans and cling film and bake for a further 5–8 minutes to make sure the shell is dried out and has an even colour. Leave to cool.
3: In a saucepan, melt the butter with the kirsch and sugar on a medium heat. Add 400g of the cherries and cook until they are very soft and broken down. This will take about 8–10 minutes. Pour the cherry mixture into a blender or food processor and whizz until smooth. Pass the purée back into the pan through a fine sieve and simmer gently to reduce the sauce until it’s thickened slightly.
4: Tip in the rest of the cherries and stir around, making sure they all get covered in the warm purée. Remove from the heat and cover the pan with cling film or a tight-fitting lid so the whole cherries can cook in their own steam. Leave the pan to cool.
5: To make the custard, bring the milk and the vanilla pod and seeds to the boil in a saucepan. In a large bowl, whisk together the egg yolks and 120g caster sugar until light and fluffy and doubled in size. Sift the flour over the whisked egg yolks and mix together. Remove the vanilla pod from the milk, then pour the milk over the egg yolks and whisk again. Pour the mixture back into the pan and return it to a medium heat. Whisk continuously as the custard thickens to make sure you get no lumps. Take it to just below boiling point – it won’t curdle like normal custard because it has flour in it, but you must cook it for 5–6 minutes to get rid of the flour taste. Take off the heat and pass the custard through a fine sieve into a bowl. Place a layer of cling film directly on top of the mixture so it doesn’t form a skin and leave to cool.
6: On a lightly floured surface, roll out two thirds of the sweet pastry to the thickness of a £1 coin. Gently line a deep 26cm pie dish with the pastry. Try not to let the pastry crack, though if you do, you can patch it up with some pastry trimmings. Line the pie dish with baking parchment or several layers of cling film then fill with ceramic baking beans or uncooked rice or pulses. Chill in the fridge for 30 minutes.
7: Preheat the oven to 170°C/Gas Mark 3. Bake the pie shell for 20–25 minutes, until golden – you may need to turn the tart around halfway through to ensure it’s evenly cooked. Remove the baking parchment and the beans and return to the oven for a further 8–10 minutes until the pastry is a dark golden brown. Remove from the oven and cool.
8: Turn the oven up to 190°C/Gas Mark 5. Place a sieve over a bowl and drain the cherries; reserve the liquor. Spread the cherries evenly in the pie shell. Pour in a little of the purée and mix together. Sprinkle the grated chocolate on top of the cherries.
9: With a large spoon, distribute the custard carefully and evenly over the cherries. Smooth with a palette knife dipped in warm water.
10: On a lightly floured surface, roll out the remaining third of the sweet pastry to the thickness of a £1 coin and place it on top of the pie. Seal around the edges. Trim the sides and pierce the top to release any steam during cooking. Brush with a little milk. Dust the top of the pie with the sugar and cinnamon and bake for 20–25 minutes.
11: Remove the pie from the oven and leave to rest for 10 minutes. Serve warm with ice cream or sorbet – don’t worry if it’s a bit messy to slice! If you prefer, you can refrigerate the pie and eat it cold too – it’s just as delicious.