Lightly grease your slow cooker with either the butter or vegetable fat.
Weigh and measure out all your ingredients except the milk and cranberries and place them in your slow cooker and give them a good stir.
Pour in 120 millilitres (1/2 cup) of your milk into your slow cooker and stir everything together.
Put your slow cooker on low and cook.
After 4 hours add inn the remaining milk and stir well. Test your rice at this point to gage how long you need to leave it. If you like your rice with a bite then it should be ready now if you like your rice a little softer then continue to cook for a little longer.
Once its ready add in your dried cranberries stir them through and serve.
This rice pudding is best eaten on the day of making but kept in the fridge it will keep up to 3 days. Reheat before serving again.