Whisk the cornflour into a little cold milk in a saucepan until smooth. Whisk in the remaining milk, sugar and vanilla.

Heat gently over a medium heat, stirring continuously and scraping the base, until thickened and just bubbling. Allow approximately 15-20 minutes.

Reduce the heat and stir for another 2 minutes. Add the optional pinch of cinnamon.

Pour into heatproof cups. Finish with your chosen toppings and serve warm.