Put the milk in a medium sized pot with the orange peel, cinnamon stick, and pinch of salt. Bring to boil and add the rinsed rice. Cook on low heat for about 1 hour and 15 minutes, or until the rice is tender. Stir occasionally, increase frequency of stirring as the cooking time increases.
Remove the cinnamon sticks and orange peel from the rice.
Add the sugar or panela and raisins, cook for 15-20 minutes, or until it is tender and creamy. Stir frequently.
Stir in the butter.
Add the condensed milk, vanilla and rum to the arroz con leche and stir well. Remove from heat.
The rice pudding or arroz con leche can be served warm or cold. Garnish with ground cinnamon, berries, dulce de leche, chocolate shavings, etc.