Boil 400ml of the milk with the sugar, the split vanilla pod and the salted butter.
Remove from the heat and add the remaning 100ml of milk and the rum.
Place the flour in a bowl and make a well in the centre. Add the egg yolks, the single whole egg and mix briefly with a whisk - it is not necessary to obtain a completely smooth mixture.
Gradually stir in the warm milk and then run the mixture through a sieve.
Set aside for a minumum of 24 hours.
Preheat the oven to 260'C.
Use a little butter to grease your moulds.
Fill about four 5ths of the mould with the batter. Cook for 6 minutes at 260'C and then turn the temperature down to 190'C and cook for a further 30 minutes.
Once cooked, leave the cannel to cool down in the moulds before serving.
«If using larger moulds for you cannel, make sure to increase the cooking time appropriately.»