Heat the oven to 200C/180C fan/gas 6. Bring the clementine juice to the boil in a small saucepan over a medium heat. Cook until it has reduced to about 50ml (this may take up to 20 mins). Leave to cool.

Unravel the puff pastry. Scatter two-thirds of the clementine zest over it. Re-roll the pastry into a tight spiral from one of the short ends, then cut along its length at 2cm intervals into 12 even rounds. On a lightly floured surface, roll each round into a roughly 10cm circle. Line the holes of a 12-hole muffin tin with the pastry rounds. Chill in the fridge until needed.

Put the eggs, egg yolks, cornflour, sugar, reduced clementine juice and the remaining zest in a pan, and whisk together to combine. Gradually whisk in the milk until the mixture is smooth, then warm over a low-medium heat until thickened and starting to simmer, about 8-10 mins. Remove from the heat, pour into a jug and leave to cool for a few minutes, whisking occasionally to prevent a skin from forming.

Fill each pastry case with custard until almost full. Bake for 18-22 mins until the pastry cases are golden and the custard has browned slightly on top. Leave to cool completely in the tin. Dust with icing sugar, before serving, if you like.