Heat the milk and butter in a saucepan.
In a bowl, mix together eggs, sugar, and vanilla bean until well combined.
Pour the warmed milk mixture into the egg mixture and mix well.
Add sifted flour and rum, then mix evenly.
Let the batter rest in the refrigerator for 12 to 24 hours.
Brush butter onto the canelé molds and pour in the batter.
Bake at 200°C for 10 minutes, then lower to 180°C and bake for an additional 40–50 minutes.
Remove the finished canelé from the mold and let them cool.