Spray an 8x8 inch square pan with cooking spray, then lay a double layer of cling film into the pan. Spray again with cooking spray and leave to one side.
Place the condensed milk into a deep saucepan and break the white chocolate into it. Place over a low heat and stir frequently until the chocolate has melted.
Once the chocolate has melted and the mixture is smooth and combined, add in the butter, peppermint extract and salt. Mix until the the butter has melted completely.
Pour the mixture into your prepared pan and smooth into an even layer.
Place the candy canes into a large bowl, or Ziploc bag and hit with a rolling pin to crush them up. You can crush as much as you want, I like to have some tiny pieces, like dust and then some large chunks.
Once the candy canes are smashed, sprinkle over the top of the fudge and gently press to stick them into the top.
Leave the fudge to cool for 30 minutes, before placing into the fridge to set, this will take around 6 hours.
Once the fudge is set, gently lift out the fudge and place on a cutting board. Peel away the cling film and place the fudge on the cutting board. Get a large jug of hot water, a long knife and some kitchen paper before attempting to slice!
Dip the knife into the hot water for a good 10 seconds, then dry it with the kitchen paper. Cut the fudge into 16-24 squares. I usually get 2 cuts from the knife before having to reheat it in the water. I would advise using a warm knife to cut as it stops the knife sticking to the fudge.
White Chocolate Candy Cane Fudge will keep in an airtight container, at room temperature, for a week.