For the pastry
- 200g plain flour, plus extra for rolling
- 1 tbsp golden caster sugar
- 100g unsalted butter, chilled
For the filling
Tip the flour and sugar into a large mixing bowl. Slowly add around 150ml very cold water, or just enough so that you have a soft dough that picks up all the crumbs from the outside of the bowl, but isn’t too sticky to handle.
Wrap the dough in cling film and chill while you coarsely grate the butter. Roll the dough out onto a floured work surface to a 30 x 40cm rectangle, then sprinkle the surface with half the grated butter to form an even layer. Don’t worry if the butter clumps together, just make sure the pieces are evenly distributed. With the shorter edge facing you, fold the top third of the dough towards you to the centre and the bottom third up over it. Give the dough a quarter turn, then roll out to the same size as before, sprinkle with the rest of the butter and repeat. Wrap the dough tightly in cling film and chill for 30 mins while you make the filling.
Put the egg yolks and cornflour in a large heatproof mixing bowl and whisk in the sugar until pale and thick. Split the vanilla pod in half along the length and scrape out the seeds. Put the seeds in a medium-sized saucepan, along with the empty pod, the cinnamon stick and the lemon zest. Pour the milk and cream over the aromatics, stir and heat very gently until only just simmering. Pour the hot mixture over the egg yolks and whisk well. Pour the custard back into the pan and warm through for 2-3 mins or until thickened slightly to a consistency similar to double cream. Strain the custard through a sieve into a large jug and set aside, covered with cling film.
Heat oven to 200C/180C fan/gas 6. Grease a 12-hole muffin tin with butter. Take your pastry out of the fridge and roll it flat to 40 x 20cm. Starting at the longest side, roll it up tightly to make a long roll of pastry. Trim the ends, then cut into 12 pieces, and turn them cut-side up on the work surface, so the spiral is facing upwards. Carefully flatten them out until they are big enough to line the holes in the muffin tin, trying not to skew the spiral shape too much. Press into the tins, then carefully pour in the custard mixture, filling each tart almost to the top.
Bake for 30 mins or until the pastry is cooked through and the custard is just starting to puff up but not balloon.
Remove from the oven and allow them to cool and sink gently back into shape. Serve cold with coffee.