- Heat the milk with the vanilla bean paste or scraped seeds of the vanilla bean over medium-low heat to infuse the milk with vanilla flavour, whisking often, for 15 minutes, but do not allow the liquid to reduce. Remove the pan from the heat and whisk in the sugar and butter until the sugar has dissolved and the butter has melted. Whisk in the egg, egg yolk and rum, followed by the flour. Strain the batter through a sieve and chill for 12 to 24 hours.
- Preheat the oven to 450F (232C). Brush the insides of your cannel tins generously with butter and freeze then tins for 10 minutes.
- Give the batter a gentle whisk to recombine it (it will have separated during chilling) and pour the batter into the molds, dividing it evenly between them. Bake the cannelé for 10 minutes at 450F (232C), then reduce the oven temperature to 375F (180C) and continue to cook for another 35 to 40 minutes until the tops of the cannelés are a deep, dark brown colour. Cool the cannelés in their tins for 10 minutes, then tip them out onto a rack to cool completely.
The cannelés are best enjoyed the day they are baked.