To prepare the canelés, you need to plan it on two days.
The first day, start by bringing the milk to a boil with the vanilla beans.
Let the beans infuse.Mix together the flour and sugar.Add the egg yolks and mix well.Add the milk to this preparation.Add butter and rum.Place in a bowl in the fridge overnight.The next day, preheat the oven at 220°C.Mix the preparation together.
Grease the moulds with butter.Fill them with the preparation (not right at the top as they rise and fall back again).Let them cook for about 1 hour.
Check regularly (you might prefer them less dark, but be assured that the dark colour does not affect the moist inside.Remove from the molds when still hot and let them cool down.