Preheat your oven to 240ºC (v hot!).
Unroll your puff pastry then roll up lengthways into a spiralled log.
Cut into 4 pieces and place each piece in a muffin tin with the swirl facing up.
Press the pastry into the tin and up the sides into a tart shape, hand-moulding into the necessary shape and trying to make the pastry as even as possible.
Mix the custard, lemon zest and cinnamon together then spoon 2 tbsp into each tart, so the custard reaches almost the top of the pastry but not quite.
Bake for 25-30 minutes until the pastry is a deep golden and the custard has caramelised slightly.
Allow to cool before dusting over icing sugar (and a little extra cinnamon if you fancy) and eating.
