Slowly bring the plant-based drink to the boil over a medium heat in a saucepan with the lemon zest and cinnamon stick. Meanwhile, separate out the egg yolks and beat them in a bowl with the sugar and cornflour until you have a smooth paste without any lumps.
When the plant-based drink has boiled for a few minutes, strain to remove the lemon zest and cinnamon stick and then add the egg paste. Turn down the heat to low and stir for a few minutes as it thickens. When it starts to boil, leave it on the heat for another minute.
Pour the mixture into ramekins and leave to cool. Before serving, sprinkle some sugar on top and caramelise with a kitchen blowtorch.