Break the white chocolate into chunks and place it into a saucepan with the condensed milk.
Place the saucepan over low heat and stir gently until the chocolate has melted and the mixture is thick. Alternatively, you can do this in the microwave, stirring every 20 seconds or so to prevent burning.
Remove from the heat and stir in most of the cranberries, saving a few to top.
Transfer the fudge mixture to your lined tin then top with the remaining cranberries.
Refrigerate for 4 hours until firm, then cut into squares and enjoy.
Video
Notes
Store in an airtight container in the refrigerator for up to 2 weeks.